Numbers 9:3-5

Amplified Bible

³ On the fourteenth day of this month ^[a]at twilight, you shall keep it at its appointed time; according to all its statutes and ordinances you shall keep it.” ⁴ So Moses told the Israelites to observe the Passover. ⁵ They observed the Passover on the fourteenth day of the first month at twilight in the Wilderness of Sinai; in accordance with all that the Lord had commanded Moses, so the Israelites did.