Therefore let no man glory in men. For all things are yours;
Let no man glory in men - as the sphere in which he glories; resuming 1 Corinthians 3:4: cf. 1 Corinthians 1:12; 1 Corinthians 1:31, where the true object of glorying is stated: "THE LORD." Also 1 Corinthians 4:6.
For all things - not only all men. For you to glory in men is lowering yourselves from your high position as heirs of all things. All (including your teachers) belong to Christ, and therefore to you, by your union with Him: He makes them and all things work together for your good (Romans 8:28). Ye are not for the sake of them, but they for you (2 Corinthians 4:5; 2 Corinthians 4:15). They belong to you, not you to them.