1 Samuel 21:4

And the priest answered David and said, There is, no common bread under mine hand, no kind of ordinary bread, such as was commonly used for food, but there is hallowed bread, for apparently the cakes of showbread had just been replaced by a fresh set, Leviticus 24:8, the ordinance requiring that the bread which had been removed be eaten by the priests in the Holy Place; if the young men have kept themselves at least from women, Leviticus 15:18. The high priest was willing to make an exception in this case, but felt that he must insist upon ceremonial, Levitical purity.