1 Samuel 21:2
And David said unto Ahimelech the priest, The king hath commanded me a business, and hath said unto me, Let no man know any thing of the business whereabout I send thee, and what I have commanded thee: and I have appointed my servants to such and such a place.
David told Ahimelech the priest that the king had commanded him a secret business about which no man must know anything, and that he had appointed his servants to a certain place. The claim was untrue, for out of fear of being discovered he resorted to deception in order to obtain refuge and help, and in doing so he failed to trust God. That deception helped bring about the death of the high priest.
The verse belongs to the episode in which David, hungry and accompanied by his men, was given the consecrated bread from the sanctuary that was ordinarily reserved for priests, and he and his companions ate it. Because of their urgent hunger and need, eating the sacred bread was guiltless and justifiable despite its ordinary restriction. The episode establishes that supplying urgent human need in the course of serving God does not violate God's service even when ordinary rules would forbid the act. By the same principle, an urgent need like David's can justify the emergency use of tithe, though this does not excuse careless neglect of tithing. David's receiving and sharing the sacred bread when hungry was later appealed to in defense of the hungry disciples who ate grain on the Sabbath.