Exodus 12:15

12:15 For seven days you must eat bread made without yeast. Surely on the first day you must put away yeast from your houses because anyone who eats bread made with yeast from the first day to the seventh day will be cut off from Israel.

Exodus 31:14

31:14 So you must keep the Sabbath, for it is holy for you. Everyone who defiles it must surely be put to death; indeed, if anyone does any work on it, then that person will be cut off from among his people.