John Gill Commentary 2 Samuel 13:33

"Now therefore let not my lord the king take the thing to his heart, to think that all the king`s sons are dead; for Amnon only is dead." — 2 Samuel 13:33 (ASV)

Now therefore let not my lord the king take the thing to his
heart
Neither suppose it, nor be troubled for it:

to think that all the king's sons are dead :
which was not to be thought, nor could any good reason be given for such a supposition

for Amnon only is dead ;
he repeats it again with great assurance, which seems to confirm the suspicion of him before suggested; though some think he said this not from certain knowledge, but by conjecture.