The Only Mitzvah at Night

A man once told the Magid of Mezheritch zy”a that he suffered great nisyonos every night and he could not overpower his urges. The Magid told him to wash for bread every night so that he could recite Birchas Hamazon, as this is the only mitzvas asei d’ohraysa that one can do at night, and it would serve to protect him.