3:10-15 The apostle was a wise master-builder; but the grace of God made him such. Spiritual pride is abominable; it is using the greatest favours of God, to feed our own vanity, and make idols of ourselves. But let every man take heed; there may be bad building on a good foundation. Nothing must be laid upon it, but what the foundation will bear, and what is of a piece with it. Let us not dare to join a merely human or a carnal life with a Divine faith, the corruption of sin with the profession of Christianity. Christ is a firm, abiding, and immovable Rock of ages, every way able to bear all the weight that God himself or the sinner can lay upon him; neither is there salvation in any other. Leave out the doctrine of his atonement, and there is no foundation for our hopes. But of those who rest on this foundation, there are two sorts. Some hold nothing but the truth as it is in Jesus, and preach nothing else. Others build on the good foundation what will not abide the test, when the day of trail comes. We may be mistaken in ourselves and others; but there is a day coming that will show our actions in the true light, without covering or disguise. Those who spread true and pure religion in all its branches, and whose work will abide in the great day, shall receive a reward. And how great! how much exceeding their deserts! There are others, whose corrupt opinions and doctrines, or vain inventions and usages in the worship of God, shall be made known, disowned, and rejected, in that day. This is plainly meant of a figurative fire, not of a real one; for what real fire can consume religious rites or doctrines? And it is to try every man's works, those of Paul and Apollos, as well as others. Let us consider the tendency of our undertakings, compare them with God's word, and judge ourselves, that we be not judged of the Lord.
14. abide—abide the testing fire (Mt 3:11, 12).
which he hath built thereupon—which he built on the foundation.
reward—wages, as a builder, that is, teacher. His converts built on Christ the foundation, through his faithful teaching, shall be his "crown of rejoicing" (2Co 1:14; Php 2:16; 1Th 2:19).