This is the ordinance of Passover
Exo 12.1-43
14th day of the first month at even. A holy convocation.
Lev 23.5-8
Keep the feast without leaven. Leaven; malice and wickedness. Unleavened, sincerity and truth
1 cor 5.7-8
Seven days shalt thou eat unleavened bread. In the time if the month of Abib
Exo 34.18
In the first month, on the fourteenth day at even ye shall eat unleavened bread, until the one and twentieth day of the month
Exo 12.18
Seven days, no leaven found in your home
Exo 12.19
Paul kept the feast of unleavened bread
Act 20.6