Then Moses summoned all the elders of Israel and said to them, “Go, select an animal from the flock according to your families, and slaughter the Passover animal.
You must observe it at its appointed time on the fourteenth day of this month at twilight; you are to observe it according to all its statutes and ordinances.”
and they observed it in the first month on the fourteenth day at twilight in the Wilderness of Sinai. The Israelites did everything as the Lord had commanded Moses.