- Matthew 12:3-4
But he said unto them, Have ye not read what David did, when he was an hungred, and they that were with him;
How he entered into the house of God, and did eat the shewbread, which was not lawful for him to eat, neither for them which were with him, but only for the priests?
- Luke 6:3-4
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;
How he went into the house of God, and did take and eat the shewbread, and gave also to them that were with him; which it is not lawful to eat but for the priests alone?
- Mark 2:25-26
And [Jesus] said unto them, Have ye never read what David did, when he had need, and was an hungred, he, and they that were with him?
How he went into the house of God in the days of Abiathar the high priest, and did eat the shewbread, which is not lawful to eat but for the priests, and gave also to them which were with him?
Matthew and Luke are in harmony, but Mark account specifically mentions that this incident took place "in the days of Abiathar the high priest."
The problem lies not in Mark's variance from Matthew and Luke (since this presents no difficulty) but in the fact that Abiathar is not presented as the high priest in the Old Testament account:
1 Samuel 21:1-3
Then came David to Nob to Ahimelech the priest: and Ahimelech was afraid at the meeting of David, and said unto him, Why art thou alone, and no man with thee?
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.
Now therefore what is under thine hand? give me five loaves of bread in mine hand, or what there is present.
Since Mark is believed to be the earliest gospel, it is often argued that this reference to Abiathar was a mistake (either on the part of Mark or Jesus himself) which the later gospels took care to correct in their respective versions.