Deuteronomy 8:2

8:2 Remember the whole way by which he has brought you these forty years through the desert so that he might, by humbling you, test you to see if you have it within you to keep his commandments or not.

Deuteronomy 16:4

16:4 There must not be a scrap of yeast within your land for seven days, nor can any of the meat you sacrifice on the evening of the first day remain until the next morning.