Adam Clarke on John 1:20

He confessed, and denied not; but confessed - A common mode of Jewish phraseology. John renounces himself, that Jesus may be all in all. Though God had highly honored him, and favored him with peculiar influence in the discharge of his work, yet he considered he had nothing but what he had received, and therefore, giving all praise to his benefactor, takes care to direct the attention of the people to him alone from whom he had received his mercies. He who makes use of God's gifts to feed and strengthen his pride and vanity will be sure to be stripped of the goods wherein he trusts, and fall down into the condemnation of the devil. We have nothing but what we have received; we deserve nothing of what we possess; and it is only God's infinite mercy which keeps us in the possession of the blessings which we now enjoy.