This Bible contradiction is from the Skeptic's Annotated Bible.
After he hacked Agag to pieces
1 Samuel 15:35 View context
And Samuel came no more to see Saul until the day of his death: nevertheless Samuel mourned for Saul: and the LORD repented that he had made Saul king over Israel.
When Saul prophesied naked
1 Samuel 19:24 View context
And he stripped off his clothes also, and prophesied before Samuel in like manner, and lay down naked all that day and all that night. Wherefore they say, [Is] Saul also among the prophets?