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.

Deuteronomy 28:66

28:66 Your life will hang in doubt before you; you will be terrified by night and day and will have no certainty of surviving from one day to the next.