John Gill Commentary 2 Kings 12:21

"For Jozacar the son of Shimeath, and Jehozabad the son of Shomer, his servants, smote him, and he died; and they buried him with his fathers in the city of David: and Amaziah his son reigned in his stead." — 2 Kings 12:21 (ASV)

For Jozachar the son of Shimeath
Said to be an Ammonitess, and this man's name Zabad, (2 Chronicles 24:26) ,

and Jehozabad the son of Shomer, his servants ;
who is said in the same place to be the son of Shimrith a Moabitess:

these smote him, and he died ;
justly did he fall by the hands of such persons for his idolatry:

and they buried him with his fathers in the city of David ;
but not in the sepulchres of the kings, because of his idolatry and murder of a priest of the Lord:

and Amaziah his son reigned in his stead ;
the conspirators not seeking the kingdom, but vengeance on him for his sins, which, whether right in them to do, was suffered by the Lord.