1 Samuel 29:6

As the Lord liveth; he swears by Jehovah; either because he did acknowledge their Jehovah to be a God, being, it may be, convinced and instructed therein by David, though he did worship Dagon with him, and above him: or because this was David's God, and therefore he swore by him; partly out of complaisance with David, that he might receive his unwelcome message to him with less offence; and partly that this oath might gain more credit to his words with David. Thy going out and thy coming in with me, i.e. thy whole conversation with me. See 1 Samuel 18:13, and many other places where that phrase is used. Since the day of thy coming unto me; though before that time there was evil in thee towards me and my people.