Luke 6:3
And Jesus answering them said, Have ye not read so much as this, what David did, when himself was an hungred, and they which were with him;
Cross-reference
1 Samuel 21:3-6 is the actual event Jesus references here: David eating consecrated bread from the tabernacle to satisfy hunger.
Matthew 12:3 parallel account of Jesus citing David eating showbread — the same response to the Pharisees' Sabbath accusation.
Matthew 12:5 adds Jesus' second argument: priests break Sabbath without guilt, reinforcing that human need can override ritual law.
Mark 2:25 gives the parallel account of Jesus citing David's actions — nearly identical wording, reinforcing the same argument.
Mark 2:26 provides the parallel account with the detail that Abiathar was high priest, clarifying the historical context of David's action.
1 Samuel 21:6 is the OT source Jesus quotes: David ate the consecrated bread when fleeing Saul, illustrating the precedent for breaking ceremonial law.