The Sharia of Moses in the TORA
Part 2 - The 365 Prohibitions of the Tora
325 - WORKING ON ATZERETH
Leviticus 23:21 -- “And you shall proclaim on the same day that it is a holy convocation to you. You shall do no customary work on it. It shall be a statute forever in all your dwellings throughout your generations.”
By this prohibition, it is forbidden to do work on Atzereth (i.e. Shevuoth).