"a" sabbath: proves that the weekly Sabbath did not exist before Ex 16:23

The first time any Jewish holy day is mentioned in scripture, it always lacks the definite article (a Sabbath).

All the Jewish holy days are never introduced the first time in scripture with the definite article "the" but with the indefinite "a" or "an".
The indefinite article is used both before and after something has been instituted, but the definite article (THE Sabbath) is never used the first time something is introduced.
This powerful argument proves that the weekly Sabbath did not exist before Ex 16:23.
What makes it irrefutable, is the fact that every Jewish Holy Day follows this same pattern!

first time instituted	after instituted
tomorrow is a Sabbath: Ex 16:23	"the" Lord has given you the Sabbath: Ex 16:29
A solemn rest "a" holy Sabbath: Ex 17:22; Lev 16:25	"the" Sabbath: Ex 20:11
"a" memorial: Lev 12:30	afterwards, the Lord's Passover
"an" holy convocation: Lev 23:21	the day of Pentecost: Acts 2:1
Unleavened bread: "a" feast: Ex 12:40	afterward, the feast: Lev 23:6
In-gathering: "a" feast	the feast: Heb 8:18
"an" alter Gen 8:20	the altar: Gen 8:20
"a" Day of atonement: Lev 23:27

We Speak truth in LOVE
"you are seeking to kill Me, a man who has told you the truth" Jn 8:40