Augustine of Hippo — as excerpted in the Catena Aurea on John 21:15-17

“(Tract. cxxiii) They who feed Christ’s sheep, as if they were their own, not Christ’s, shew plainly that they love themselves, not Christ; that they are moved by lust of glory, power, gain, not by the love of obeying, ministering, pleasing God. Let us love therefore, not ourselves, but Him, and in feeding His sheep, seek not our own, but the things which are His. For whoso loveth himself, not God, loveth not himself: man that cannot live of himself, must die by loving himself; and he cannot love himself, who loves himself to his own destruction. Whereas when He by Whom we live is loved, we love ourselves the more, because we do not love ourselves; because we do not love ourselves in order that we may love Him by Whom we live.”