'Leaven' in the Bible

You shall bring from your dwellings for a wave offering two [loaves of] bread {made with} two-tenths [of an ephah] of finely milled flour; they must be baked with leaven--[the] firstfruits {belonging to} Yahweh.

And leaven shall not be seen with you in any of your territory for seven days, and none of the meat that you will slaughter on the evening on the first day shall remain overnight until morning.