Numbers 9:3

9:3 In the fourteenth day of this month, at twilight, you are to observe it at its appointed time; you must keep it in accordance with all its statutes and all its customs.”

Numbers 9:6

9:6 It happened that some men who were ceremonially defiled by the dead body of a man could not keep the Passover on that day, so they came before Moses and before Aaron on that day.

Numbers 29:12

The Feast of Temporary Shelters

29:12 “‘On the fifteenth day of the seventh month you are to have a holy assembly; you must do no ordinary work, and you must keep a festival to the Lord for seven days.