1 Samuel (Author Compiled by Isaiah from records of Samuel, David, Nathan, and Gad.)
26:21And Saul said, I have sinned: return, my son David; for I will no more do thee harm, because my life was precious in thine eyes this day: behold, I have acted foolishly, and have erred exceedingly.
Original from The Bible Foundation - bf.org. They claim public domain status for their original text.