Numbers 9:2-5

“Have the Israelites celebrate the Passover at the appointed time. Celebrate it at the appointed time, at twilight on the fourteenth day of this month, in accordance with all its rules and regulations.” So Moses told the Israelites to celebrate the Passover, and they did so in the Desert of Sinai at twilight on the fourteenth day of the first month. The Israelites did everything just as the LORD commanded Moses.