A Passover Note on Deuteronomy 16:4

“And no leaven shall be seen among you in all your territory for seven days, nor shall any of the meat which you sacrifice the first day at twilightremain overnight until morning.” ~Deuteronomy 16:4
…Some are trying to use the verse above to promote the false teaching that Passover is on Day 15 / Month 1…

It would be hard to understand the eight days of Passover and Unleavened Bread from Deuteronomy alone. In order to rightly divide the Word of Truth we need to read and study everything that Exodus, Leviticus and Numbers has to say on the subject. The instructions in these books will help clarify the account in Deuteronomy.

Deuteronomy 16:1-8 
“1 Observe the month of Abib, and keep the Passover to יהוה your Elohim[on Day 14 / Month 1], for in the month of Abib יהוה your Elohim brought you out of Egypt by night. 2 Therefore you shall sacrifice the Passover to יהוהyour Elohim, from the flock and the herd, in the place where יהוה chooses to put His name. 3 You shall eat no leavened bread with it; [Then from Day 15 / Month 1 to Day 21 / Month 1 for] seven days you shall eat unleavened breadwith it, that is, the bread of affliction (for you came out of the land of Egypt in haste), that you may remember the day in which you came out of the land of Egypt [Day 21 / Month 1] all the days of your life. 4 And no leavenshall be seen among you in all your territory for seven days [Day 15 / Month 1 to Day 21 / Month 1], nor shall any of the meat which you sacrifice the first day [Day 14 / Month 1] at twilight remain overnight until morning. 5 “You may not sacrifice the Passover within any of your gates which יהוה your Elohim gives you; 6 but at the place where יהוה your Elohim chooses to make His name abide, there you shall sacrifice the Passover at twilight [beginning Day 14 / Month 1], at the going down of the sun, at the time you came out of Egypt. 7 And you shall roast and eat it in the place which יהוהyour Elohim chooses, and in the morning you shall turn and go to your tents. 8 Six days you shall eat unleavened bread [Day 15 / Month 1 to Day 20 / Month 1], and on the seventh day [Day 21 / Month 1] there shall be a sacred assembly to יהוה your Elohim. You shall do no work on it.
LEFT RAMESES
The children of Yisrael left Rameses on Day 15 / Month 1:
Numbers 33:3
They departed from Rameses in the first month, on the fifteenth day of the first month; on the day AFTER the Passover the children of Yisrael went out with boldness in the sight of all the Egyptians. 
LEFT EGYPT
The children of Yisrael left the land of Egypt 
when they crossed the Red Sea on Day 21 / Month 1:
Exodus 12:16-18
16  On the first day [Day 15 / Month 1] there shall be a set apart convocation, and on the seventh day [Day 21 / Month 1] there shall be a set apart convocation for you. No manner of work shall be done on them; but that which everyone must eat — that only may be prepared by you. 17 So you shall observe the Feast of Unleavened Bread, for on this same day [Day 21 / Month 1] I will have brought your armies out of the land of Egypt. Therefore you shall observe this day throughout your generations as an everlasting ordinance.