Matthew 22:39

Nor did He only teach the first and great commandment, but added that there was a second like unto the first, Thou shall love thy neighbour as thyself. But if Whoso loveth iniquity hath hated his own soul, (Ps. 11:5.) it is manifest that he does not love his neighbour as himself, when he does not love himself.

Or otherwise; That the second command is like the first signifies that the obligation and merit of both are alike; for no love of God without Christ, or of Christ without God, can profit to salvation. It follows, On these two commandments hang all the Law and the Prophets.

(de Doctr. Christ. i. 30.) It is clear that every man is to be regarded as a neighbour, because evil is to be done to no man. Further, if every one to whom we are bound to show service of mercy, (vid. Rom. 13:10.) or who is bound to show it to us, be rightly called our neighbour, it is manifest that in this precept are comprehended the holy Angels who perform for us those services of which we may read in Scripture. Whence also our Lord Himself would be called our neighbour; for it was Himself whom He represents as the good Samaritan, who gave succour to the man who was left half-dead by the way.

(de Trin. viii. 6.) He that loves men ought to love them either because they are righteous, or that they may be righteous; and so also ought he to love himself either for that he is, or that he may be righteous. And thus without peril he may love his neighbour as himself.

(de Doctr. Christ, i. 22.) But if even yourself you ought not to love for your own sake, but because of Him in whom is the rightful end of your love, let not another man be displeased that you love even him for God's sake. Whoso then rightly loves his neighbour, ought to endeavour with him that he also with his whole heart love God.