Exodus 34:22 And you shall observe the feast of weeks, of the first fruits of wheat harvest, and the feast of ingathering at the year's end.
Leviticus 23:5,16,34 In the fourteenth day of the first month at even is the LORD's passover...
Deuteronomy 16:16 Three times in a year shall all your males appear before the LORD your God in the place which he shall choose...