20:5 new moon; David, in fear of his life, came to Jonathan as soon as he could not be seen.  Therefore it was night when he arrived for his secret conference.   The new moon had been seen shortly after sunset fulfilling its duty to be a "light" sign for the beginning of the month (Gen. 1:14), so that the next day would be the first day of the month, so David knew that a feast would be held on the first day of the month.  

The text says "day to come" because Israel reckoned its calendar day from daybreak to daybreak.  The calendar day for the first day of the month, would therefore begin in the morning.  See Genesis 1:5.  The following will illustrate:

 

20:5 third setting; David means the sunset on the third day of the month.  For by being in a secret hiding place during the third day, Jonathan will be free to approach him with news of Saul's disposition, because two days would be kept as a feast, though in this case, the first day would be the official new moon day.

 

20:12 the third: the third day of the month is meant.

20:18 new moon: David and Jonathan were talking just after the new moon had been seen at night.  When Jonathan says "day to come" he means the very next day starting in the morning will be the "new moon day".

The text says "day to come" because Israel reckoned its calendar day from daybreak to daybreak (excepting Sabbaths). The calendar day for the first day of the month, would therefore begin in the morning.  See Genesis 1:5.

20:19 make three; again the third day of the month is meant.  Jonathan tells David to move to a hiding place they both know about on the third day.  It is the same hiding place that David used on Saul first ordered his servants to kill David, and had to be persuaded not to by Jonathan.

20:19 day of the deed; this refers to the day in Chapter 19:1 that Saul ordered his servants to kill David.  David is to use the same hiding place on the third day of the month.

20:24 the new moon came; the crescent had already been seen the preceding night.  This phrase means that the new moon day came, i.e. the day of the feast on which the new moon was celebrated, also the first day of the month.   Israel 's calendar day was from daybreak to daybreak (cf. Genesis 1:5), and so the new moon "day" was counted as the day following the night in which the new moon was witnessed.

20:27 the second; this means the second day of the month, i.e. the day after the new moon day, which was the first day of the month.  While the court feasted for two days, this fact should not be used to infer that there were two actual days of the official "new moon";  the phrase here does not mean "second day of the new moon", but simply "the second" day of the month.  For the former phrase, see vs. 34.  The feasting for two days is similar to the later Jewish custom of celebrating two days for every feast, so as to be sure with keeping up with the actual new moon in the case of doubt.  But only one of these days will be considered the official new moon.   In the case of this passage, it was known which day was the new moon, because it had clearly been seen.  However, the custom of feasting two days was kept. 

This was likely a case where the previous month had 29 days, and the new moon was seen in the night following the 29th day.   If the moon had not been seen, then the two feasting days would have been on the 30th day of the old month, and the 1st of the new month.  But as it was, the two feasting days were on the 1st of the new month and on the second.  The custom of two feast days was imposed because many localities could not be sure which day was the new moon.  This custom was still followed, however, when the actual new moon day was known for certain.

Note: The Stone Edition Tanach translates, "It was the day after the New Moon, the second [day of the month]".

20:34 the second day of the new moon;  In this case, it turned out to be the second day of the month, which is a possible translation of this phrase, but less likely due to usages in Ezekiel 46:1, 6.  It is only that the "second day of the new moon" here coincided with the "second day of the month".  "Second day of the official new moon" would be nonsensical since it was clear that the new moon day was the preceding day in this case.  The Hebrew here is: בְּיוֹם־הַוֹחדֶש הַשֵּׁנִי.  (*Note the red letter means the MT spells defectively.)  JPS (1917) translates, "second day of the month" here.  Note: The Stone Edition Tanach translates, "on that second day of the month", possible, but not likely.

The explanation for the phrase "second day of the new moon" is that it is a technical phrase for a second day kept as a feast in the case of doubt when the new moon really was.  The custom became so frequent, that even in those cases when the new moon day was known, the second day of the new moon would still be observed as a feast.

Only one day of the month, therefore, will be proclaimed the new moon day, but the feasting custom will be either the 30th day of the old month and the 1st of the new in the case that the previous month has 30 days, or the 1st of the new and the 2nd of the new in the case that the previous month has 29 days.   In every case the two days of feasting were day 29 + 1 of the old month, and day 29 + 2 of the old month.  If the old month really had 30 days, then "the second day of the new moon" would be regarded as the official day of the new moon.

None of this is to say that there were actually two real new moon days.  If the new moon day was not clear, then day 29+1 would be the "first day of the new moon" and day 29+2 the "second day of the new moon".   These were technical phrases for potential official new moon days, which were both treated as official until it became clear which one was the official day. Obviously the new moon can appear on only one of the two days.   As a technical phrase, they mean the two days on which the moon CAN renew, but its usage is connected with potentiality, it cannot necessarily be concluded from it that the moon DID renew on that day, unless it is stated which day was the new moon.  The following will illustrate:

 

It should also be clear that the new moon appears in the night before the new moon day as a sign that the new month will begin.  For the Almighty created the sun and moon as "lights" to be for "signs" (cf. Genesis 1:14).  A "sign" indicates something that is coming, not something that is past.   When the light of day appears, this is a sign of the coming day.  When the stars appear, a sign of the coming night, and when the new moon appears, a sign of the coming month.  And when certain stars rise and appear a sign of the coming season.

30:1 on the third day: בַּיּוֹם הַשְּׁלִישִי;    For the one who has the eyes to see it, and the ears to hear it, this passage relates to Yeshua's death and resurrection as is the case with most of the references to "the third day" in the Scripture.   Just below the the surface of literal interpretation the passage is pregnant with hints of Messiah, remez [רֶמֶז] which connect to his crucifixion (on the 4th day of the week), and his resurrection (on the 7th day of the week), with "the third day".

Recall that Joseph interpreted the dreams of the baker and the wine master "within three days" (Gen. 40:13; 19; 20).  One was crucified, and the other was raised, both "on the third day".  From this Samuel passage, we will also observe in hindsight that both the resurrection and the crucifixion are on the third day according to the hints.   "On the third day" David discovers apparent death and destruction of all that was dear to Him.  These woes correspond to the crucifixion. 

What does the third day measure from?  It measures from the decision of the Philistines to send David on his way under suspicion of disloyalty.  

For this reason Matthew 26:2 and Mark 14:1 relate that the crucifixion was "after two days", which is just another way of saying "the third day" (cf. Hosea 6:2).  This is measured from the priestly decision to kill Yeshua lest the Romans accuse Judea of disloyalty and 'take away their nation'.  

Recall also, that Isaac was bound "on the third day" and also delivered "on the third day" (Gen. 22:4).  So if you decode Matthew 26:2 and Mark 14:1, the texts are telling us that the crucifixion was also "on the third day" from some event.   This event is recorded in Matthew 26:3-5 and Mark 14:1b-2.  The plot was hatched then, and the third day from then (counting inclusively) was when it came to fulfillment.   It was the third day from the decision to put Yeshua to death that it came to pass.  We can relate this decision to the divine decision to test Abraham, which came to fulfillment "on the third day".

30:6 stoning him;  Yeshua would have been stoned on the cross, as this was the Jewish custom for one who was judged for a capital crime.

30:12 three days and three nights;

 שְׁלשָׁה יָמִים וּשְׁלשָׁה לֵילוֹת;   It should not be surprising that this "three days and three nights" relates to Yeshua's death and resurrection just like the Jonah passage.   Ironically, the Constantinian Sunday religion appeals to this passage for the inclusive counting of Sunday as the third day from Friday.   There is only one problem, though, and this is that Yeshua was raised before the sun came up, while "still dark" (John 20:1).  So there isn't even a part of a third day to count. 

The hint is in the words "then his spirit returned", which is like the word sheol in Jonah.  Jonah wasn't literally in the grave.  The literalness of sheol is reserved for the Messianic remez.  Likewise, the spirit of this Egyptian slave did not literally return, because it never left in death.  The literalness of the spirit returning to the body is also reserved for a Messianic hint of Yeshua's resurrection.

Note also that the order "three days" before "three nights" implies a calendar day where day comes before night, i.e. daybreak to daybreak.  Otherwise, the text would have said, "three nights and three days".

30:13 the third day;  it is not clear whether the Egyptian is counting forward or backward here.  He means either today is the third day, or that he counts three days back.  We will see shortly that the found this man and "revived" him during the night, just before dawn.  If the Egyptian is counting day as "daylight", then he counts backward.  The day before that night counts as 1,  and before that as 2, and before that as the 3rd.  If the Egyptian is counting forward, then he is counting calendar days using the Egyptian definition of a calendar day (daybreak to daybreak), which is also the common biblical definition of a calendar day in normal use.  The setting to setting day was used only in the case of Sabbaths.

Since, the Egyptian enumerates the day of his finding as 'three' or 'one', it is clear that he is counting inclusively.  The day he fell sick is counted as a part day (when it did not eat or drink), and the night he was found is counted as a part night since they fed him before the next day.

Since David commenced the battle during the twilight, it is clear that the "three days and three nights" is a little less than 72 hours.   The Egyptian was found well before sunrise, and was able to lead them to their camp.   We should not suppose that the Amalekites moved very far after abandoning the slave.  His master was a cruel man, and now had much booty, and wanted to enjoy the spoil.   He did not want to risk sickness interrupting his enjoyment, so he left the slave outside their camp, and then neglected him.

30:17 their next day;  it was previously observed that the Egyptian counted his calendar day from daybreak to daybreak in common with the Israelites.  Only in the case of Sabbaths is day reckoned from setting to setting, but this is not the standard calendar day in the Biblical period.  The standard calendar day was from daybreak to daybreak.   The text says "their next day".   Whose "next day" came at "setting".  The word "their" refers to the Amalekites.  It was their day that ended at sunset.  And David slew them from the morning twilight until the setting of their next day.

It should also be noted that whenever the word מָחֳרָת is used, for Israel , it means "day after" that begins in the morning, or "time after" that begins in the morning.  However here, it has the word "their" added to the end: מָחֳרָתָם, a textual detail that has perplexed most scholars because they do not recognize that Amalek used a different calendar day than Israel .  This is but another divine hint in the text to reinforce the fact that the Egyptian is using his native calendar day when he said "the third day", and that the narrator is reckoning "three days and three nights" according to the same type of calendar day, which begins in the morning.  I said "most" scholars, because I have located articles by others who understand it the way I have presented it here.  But we do not need their say so.  Formal logic dictates that Amalek reckoned its day from sunset, and that this is contrasted with Israel 's calendar day starting at daybreak.

We are safe in counting Yeshua's three days and three nights as starting Wednesday at daybreak, and ending on the Sabbath at daybreak, though the first day and last night are parts counted as a whole.