'Week' in the Bible

I fast twice in the week, I give tithes of all things -- as many as I possess.

And on the first of the week, the disciples having been gathered together to break bread, Paul was discoursing to them, about to depart on the morrow, he was also continuing the discourse till midnight,

on every first day of the week, let each one of you lay by him, treasuring up whatever he may have prospered, that when I may come then collections may not be made;