John Chrysostom

He calls not God to witness as though he should be doubted, but does this from his great affection, and his exceeding persuasion and confidence; for after saying that they had fellowship with him, he adds this also, "in the tender mercies of Christ," lest they should think that his longing for them was for this cause, and not simply for their own sake. And what mean these words, "in the tender mercies of Christ"? They stand for "according to Christ." Because ye are believers, because ye love Christ, because of the love that is according to Christ. He does not say "love," but uses a still warmer expression, "the tender mercies of Christ," as though he had said, "having become as a father to you through the relationship which is in Christ." For this imparts to us bowels warm and glowing. For He gives such bowels to His true servants. "In these bowels," saith He, as though one should say, "I love you with no natural bowels, but with warmer ones, namely, those of Christ." "How I long after you all." I long after all, since ye are all of this nature; I am unable in words to represent to you my longing; it is therefore impossible to tell. For this cause I leave it to God, whose range is in the heart, to know this. Now had he been flattering them, he would not have called God to witness, for this cannot be done without peril.