Adam Clarke on Genesis 22:16

By myself have I sworn - So we find that the person who was called the angel of the Lord is here called Jehovah; See note on Gen 22:2. An oath or an appeal to God is, among men, an end to strife; as God could swear by no greater, he sware by himself: being willing more abundantly, says the apostle, to show unto the heirs of promise the immutability of his counsel, he confirmed it by an oath, that two immutable things, (his Promise and his Oath), in which it was impossible for God to lie, we might have a strong consolation, who have fled for refuge to lay hold on the hope set before us. See Heb 6:13-18.