David
Psalm 41:9BSB·traditional attribution

Even my close friend whom I trusted, the one who shared my bread, has lifted up his heel against me.

John Calvin Reformed @genevareformer

PSALM 41 David, while he was severely afflicted by the hand of God, perceived that he was unjustly blamed by men who regarded him as one who had already been condemned and devoted to eternal destruction. Under this trial he fortifies himself by the consolation of hope. At the same time, he complains partly of the cruelty, and partly of the treachery, of his enemies.

Commenting on Psalm 41:1-13

C.H. Spurgeon Reformed Baptist @princeofpreachers

Here we have a controversy between the pleader and his God. He has been a tender friend to the poor, and yet in the hour of his need the promised assistance was not forthcoming. In our Lord's case there was a dark and dreary night in which such arguments were well befitting himself and his condition.

Commenting on Psalm 41:4

C.H. Spurgeon Reformed Baptist @princeofpreachers

Yea. Here is the climax of the sufferer's woe, and he places before it the emphatic affirmation, as if he thought that such villainy would scarcely be believed. Mine own familiar friend. "The man of my peace, "so runs the original, with whom I had no differences, with whom I was in league, who had aforetime ministered to my peace and comfort.