24:1. If a man does not wear a four-cornered garment, then he is not obligated to wear Tzitzis. But it is good and proper for every person to be careful to wear a "tallis katan" [the small garment with tzitzis that is worn under a shirt] all day, (1) in order that he remember the commandment[s] every second. This is why each corner has five knots representing the five Books of the Torah, and the garment has four corners so that in any way one turns, one remembers [the commandments]. And it is proper to wear this garment (2) over one's clothes. At the very least, one should be careful to wear tzitzis (3) for prayer.