There was no bread there, to wit, in the tabernacle, where David and the priest now were. In the day when it was taken away, which was done upon the sabbath day, Leviticus 24:8; for though they might not then kindle a fire to heat the bread in, yet they might and did keep it hot in an oven that had been heated before the sabbath.
Related Commentaries of 1 Samuel 21:6
1 Samuel 21:6
6 So the priest gave him hallowed bread: for there was no bread there but the shewbread, that was taken from before the LORD, to put hot bread in the day when it was taken away.