This Bible contradiction is from the Skeptic's Annotated Bible.

Verses

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?