Then came David to Nob to Ahimelech the priest: and Ahimelech came to meet David trembling, and said to him, Why are you alone, and no man with you?
"Exodus 19:15 declares that one prerequisite for approaching holy things is to keep oneself from sexual intercourse.  Ahimelech insisted on this regulation being observed, but ignored the one about only priests being able to eat that bread."[6]