"Let the children of Israel keep the Passover at its appointed time.
Numbers 9:2
Surrounding context
9:1 Now the LORD spoke to Moses in the Wilderness of Sinai, in the first month of the second year after they had come out of the land of Egypt, saying:
9:2 "Let the children of Israel keep the Passover at its appointed time.
9:3 On the fourteenth day of this month, at twilight, you shall keep it at its appointed time. According to all its rites and ceremonies you shall keep it."