Notice that the exact day is mentioned....
And they departed from Elim, and all the congregation of the children of Israel came to the wilderness of Sin, which is between Elim and Sina; and ON THE FIFTEENTH DAY, IN THE SECOND MONTH after their departure from the land of Egypt, all the congregation of the children of Israel murmured against Moses and Aaron. And the children of Israel said to them, Would we had died smitten by the Lord in the land of Egypt, when we sat by the flesh-pots, and ate bread to satiety! for ye have brought us out into this wilderness, to slay all this congregation with hunger. And the Lord said to Moses, Behold, I will rain bread upon you out of heaven: and the people shall go forth, and they shall gather their daily portion for the day, that I may try them WHETHER THEY WILL WALK IN MY LAW OR NOT. -- Exodus 16:1-4
Now notice the next miracle. Verse 20: some tried to save a supply of manna over until next morning, contrary to God's command. "It bred worms, and stank."
Now verse 22: On the sixth day they gathered a double portion of manna.
Verse 23: Moses explained that "Tomorrow is the rest of the Holy sabbath unto the Eternal." And on this sixth day, they were commanded to lay up the Sabbath supply of food, which they did.
And, verse 24, it did not breed worms nor decay, as on the preceding five days! Here was another MIRACLE from God, showing them which is the right seventh day!
When the next morning came -- the SABBATH, Moses said (verses 25-26) "Today is a sabbath unto the Eternal: today ye shall not find it in the field. Six days ye shall gather it; but on the seventh day, which is the sabbath, in it there shall be none"
This is God walking people through the weekly sabbath schedule...
Here is an interesting tidbit...
Obviously, the 15th is seven days before the 22nd, so therefore it's a Sabbath too!
Now I am going to add another piece...
Jeremiah 31:35-36: "Thus says the Lord, who gives the sun for a light by day, and the ordinances of the moon and the stars for a light by night...If those ordinances depart from before Me, says the Lord, then the seed of Israel shall also cease from being a nation before Me forever."
Before I go further I need to explain...
Leviticus 23 should read as follows: "Speak to the children of Israel, and say to them: 'The APPOINTMENTS of the Lord, which you shall proclaim to be holy convocations, these are My APPOINTMENTS."
Regarding those four key words in Genesis 1:14 -- signs, seasons, days and years --
Signs... implying astronomical events such as eclipses, and others we observe with our eyes in the sun, moon and stars.
Seasons... appears to represent the four radical weather shifts we experience each year -- winter, summer, spring and autumn or fall. However, the Hebrew word that has been translated "seasons" implies NO SUCH THING! This word -- "MOWADAH" or miqra (Strong's #4150) -- literally means "AN APPOINTMENT..
Psalm 104:19 we find the same word -- mowadah / miqra - used SPECIFICALLY IN RELATION TO THE MOON -- He appointed the moon for seasons [mowadah / miqra ]..." by the way the English word "appointed" in that verse actually means "made" -- see Strong's #6213.. so this verse should read: "He MADE the moon for APPOINTMENTS"! Now, just what are His appointments?
The answer to this is found in Leviticus 23 --
Speak to the children of Israel, and say to them: "The FEASTS of the Lord, which you shall proclaim to be holy convocations, these are My FEASTS.
Six days shall work be done, but the seventh day is a Sabbath of solemn rest, a holy convocation. You shall do no work on it; it is a Sabbath of the Lord in all your dwellings"
A better way of translating it would have been...'The APPOINTMENTS of the Lord, which you shall proclaim to be holy convocations, these are My APPOINTMENTS."
The grave error in translating "mowadah / miqra " as "feasts" becomes apparent when you realize that in verse 3 the SOLE SUBJECT is the seventh-day Sabbath! Generally we don't think of the Sabbath as being a "feast" per se, but it actually leads the list of "feasts" in Leviticus 23.
Here is a corroboration from Ecclesiasticus 43:6-8
And then the moon, ever punctual to mark the times, an everlasting sign: It is the moon that signals the feasts, a luminary that wanes after being full. The month derives its name from hers, she waxes wonderfully in her phases, banner of the hosts on high, shining in the vault of heaven"
There are other scriptures that tie the two together...
Kings 4:23 So he said, "Why are you going to him today? It is neither THE NEW MOON NOR THE SABBATH." And she said, "It is well."
2 Chronicles 24:31 And at every presentation of a burnt offering to the Lord on the SABBATHS AND THE NEW MOONS and on the set feasts, by number according to the ordinance governing them, regularly before the Lord.
2 Chronicles 2:4: Behold, I am building a temple for the name of the Lord my God, to dedicate it to Him, to burn before Him sweet incense, for the continual showbread, for the burnt offerings morning and evening, on THE SABBATHS, ON THE NEW MOONS, and on the set feasts of the Lord our God.
2 Chronicles 8:13 According to the daily rate, offering according to the commandment of Moses, for THE SABBATHS, THE NEW MOONS, and the three appointed yearly feasts -- the Feast of Unleavened Bread, the Feast of Weeks, and the Feast of Tabernacles.
Nehemiah 10:33 "for the showbread, for the regular grain offering, for the regular burnt offering of THE SABBATHS, THE NEW MOONS, and the set feasts..."
Ezekiel 46:3 Likewise the people of the land shall worship at the entrance to this gateway before the Lord on THE SABBATHS AND THE NEW MOONS.
Amos 8:5 When will THE NEW MOON be past, that we may sell grain? And THE SABBATH, that we may trade our wheat?
We can be sure that the sun generally marks days...
God provided the basis for such measuring of time. Genesis 1:14, 15 tells us that one of the purposes of the "luminaries in the expanse of the heavens" is that they might serve for "seasons and for days and years." The solar day, the solar year, and the lunar month are thus NATURAL divisions of time, governed respectively by the daily turning of the earth on its axis, by its annual orbit around the sun, and by the MONTHLY PHASES OF THE MOON in its relation to earth and sun.