John Gill Commentary 2 Kings 9:8

"For the whole house of Ahab shall perish; and I will cut off from Ahab every man-child, and him that is shut up and him that is left at large in Israel." — 2 Kings 9:8 (ASV)

For the whole house of Ahab shall perish
Be cut off by death, and that in a violent manner, not one should escape:

and I will cut off from Ahab him that pisseth against the wall, and
him that is shut up and left in Israel ;
of these phrases, (See Gill on 1 Kings 14:10) (See Gill on 1 Kings 21:21)