The Feast of Pentecost: A Holy Convocation
Source: TTT
Leviticus 23:21
On that same day you are to proclaim a sacred assembly, and you must not do any regular work. This is to be a permanent statute wherever you live for the generations to come.
Numbers 28:26
On the day of firstfruits, when you present an offering of new grain to the LORD during the Feast of Weeks, you are to hold a sacred assembly; you must not do any regular work.