Numbers 28:16

In the first month, on the fourteenth day of the month at even, ye shall eat unleavened bread, until the one and twentieth day of the month at even.

Now the first day of the feast of unleavened bread the disciples came to Jesus, saying unto him, Where wilt thou that we prepare for thee to eat the passover?

Ye know that after two days is the feast of the passover, and the Son of man is betrayed to be crucified.