Kommentar zu Wajikra 23:6

שבעת ימים מצות תאכלו, “you will eat unleavened bread for seven days.” The unleavened bread a person eats during those seven days are accounted as his fulfilling this commandment on Passover, the exception are the thanksgiving offerings, part of which are chametz, leavened bread, and mostly unleavened wafers which may not be offered on these days.