TSK · Numbers 9:3

and ye shall keep it until the fourteenth day of the same month; and the whole assembly of the congregation of Israel shall kill it at even.

In the second month on the fourteenth day at even they shall keep it; they shall eat it with unleavened bread and bitter herbs:

Then they killed the passover on the fourteenth [day] of the second month: and the priests and the Levites were ashamed, and sanctified themselves, and brought burnt-offerings into the house of Jehovah.