David
Psalm 55:12BSB·traditional attribution

For it is not an enemy who insults me; that I could endure. It is not a foe who rises against me; from him I could hide.

John Calvin Reformed @genevareformer

12 Of a truth, it was not an enemy that cast reproach upon me He informs us of one circumstance which added bitterness to the injuries under which he suffered, that they came from the hands not only of his professed enemies, but of such as pretended to be his friends.

C.H. Spurgeon Reformed Baptist @princeofpreachers

The reader will do well to observe how accurately the psalmist described his own Psalm when he said, "I mourn in my complaint, "or rather "give loose to my thoughts, "for he proceeds from one point of his sorrow to another, wandering on like one in a maze, making few pauses, and giving no distinct intimations that he is changing the subject.

Matthew Henry Presbyterian @wholebiblehenry

David here complains of his enemies, whose wicked plots had brought him, though not to his faith's end, yet to his wits' end, and prays against them by the spirit of prophecy. Observe here, I. The character he gives of the enemies he feared. They were of the worst sort of men, and his description of them agrees very well with Absalom and his accomplices. 1.

Commenting on Psalm 55:9-15