Adam Clarke on 2 Chronicles 24:26

These are they that conspired against him - The two persons here mentioned were certainly not Jews; the mother of one was an Ammonitess, and the mother of the other was a Moabitess. Who their fathers were we know not; they were probably foreigners and aliens. Some suppose that these persons were of the king's chamber, and therefore could have the easiest access to him. It has been, and is still, the folly of kings to have foreigners for their valets and most confidential servants, and they have often been the causes of murders and treacheries of different kinds. Foreigners should be banished from the person of the sovereign by strong and efficient laws: even in this country they have often been the cause of much political wo.