Genesis 18:19 - Joseph Benson’s Commentary on the Old and New Testaments

I know Abraham that he will command his children, and his household after him This is a bright part of Abraham's character. He not only prayed with his family, but he taught them, as a man of knowledge; nay, he commanded them, as a man in authority, and was prophet and king, as well as priest, in his own house. And he not only took care of his children, but of his household: his servants were catechised servants. Masters of families should instruct, and inspect the manners of all under their roof. And this is given as the reason why God would make known to him his purpose concerning Sodom; because he was communicative of his knowledge, and improved it for the benefit of those that were under his charge.