John Wesley on Numbers 20:16

An Angel - The Angel of the Covenant, who first appeared to Moses in the bush, and afterward in the cloudy pillar, who conducted Moses and the people out of Egypt, and through the wilderness. For though Moses may be called an angel or messenger yet it is not probable that he is meant, partly because Moses was the person that sent this message; and partly because another angel above Moses conducted them, and the mention hereof to the Edomites, was likely to give more authority to their present message. In Kadesh - Near, the particle in being so often used.