Leviticus 23:3, 32

‘For six days work may be done, but the seventh day is the Sabbath of complete rest, a holy convocation (calling together). You shall not do any work [on that day]; it is the Sabbath of the LORD wherever you may be.

It is to be to you a Sabbath of complete rest, and you shall humble yourselves. On the ninth day of the month at evening, from evening to evening you shall keep your Sabbath.”