Albert Barnes Commentary 1 Samuel 26:19

"Now therefore, I pray thee, let my lord the king hear the words of his servant. If it be Jehovah that hath stirred thee up against me, let him accept an offering: but if it be the children of men, cursed be they before Jehovah: for they have driven me out this day that I should not cleave unto the inheritance of Jehovah, saying, Go, serve other gods." — 1 Samuel 26:19 (ASV)

If the Lord has stirred you up - The meaning is clear from the preceding history. An “evil spirit from God troubling him” was the beginning of the persecution, and this evil spirit was sent as punishment for Saul’s sin (1 Samuel 16:1, 14). If the continued persecution was merely the consequence of this evil spirit continuing to vex Saul, David advises Saul to seek God’s pardon and, as a result, the removal of the evil spirit by offering a sacrifice.

But if the persecution was the consequence of the false accusations of slanderers, then “cursed” be his enemies. By their actions, they drove David from the only land where the LORD was worshiped, forcing him to take refuge in the country of pagans and idolaters (28:36).