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 9:10

9:10 “Tell the Israelites, ‘If any of you or of your posterity become ceremonially defiled by touching a dead body, or are on a journey far away, then he may observe the Passover to the Lord.

Numbers 23:13

23:13 Balak said to him, “Please come with me to another place from which you can observe them. You will see only a part of them, but you will not see all of them. Curse them for me from there.”