John Gill's  Exposition of the Bible 

2 Samuel 18:10

And a certain man saw it, and told Joab, and said, Behold, I saw Absalom hanged in an oak.

And a certain man saw it,.... Saw him in the above posture, one of David's soldiers:

and told Joab, and said, Behold, I saw Absalom hanged in an oak; caught by the neck in one, out of which he could not disengage himself, but there he hung, though alive.