The mind of King David longed

Here David is referred to by his mind to emphasize his thoughts. Alternate translation: "King David longed" (See: rc://en/ta/man/jit/figs-synecdoche)

for he was comforted concerning Amnon and his death

"because he was no longer grieving about Amnon being dead." This refers to three years after Absalom fled to Geshur.