Leviticus

Speak unto the children of Israel, and say unto them, Concerning the feasts of the Lord, which ye shall proclaim to be holy convocations, even these are my feasts.

These are the feasts of the Lord, even holy convocations, which ye shall proclaim in their seasons.

To every thing there is a season, and a time to every purpose under the heaven:

And when Aaron saw it, he built an altar before it; and Aaron made proclamation, and said, To morrow is a feast to the Lord.

Three times in a year shall all thy males appear before the Lord thy God in the place which he shall choose; in the feast of unleavened bread, and in the feast of weeks, and in the feast of tabernacles: and they shall not appear before the Lord empty: