David is fleeing from the angry King Saul who has threatened to kill him (Read chapters 18-20 for background describing why Saul is so mad and about the relationship between David and Saul's son, Jonathan).
David goes to a priest for help, but lies to him for the reason why he wants to keep his presence secret. When David tells the priest he needs five loaves of bread to sustain him during his mission. The priest tells him that the only bread they have on hand is the holy bread that is needed for a ritual and there's no one available that day to make any more. David then asked if the priest had any weapons available. The priest told him that the only weapon they had was the Goliath's and that if David wanted it, he could have it. David wanted it.
Questions arose for me. 1) Why did the lectionary compilers put this passage in a discussion of communion? 2) What is the motive that we have for joining in the Lord's Supper? What sustenance are we seeking?