John Calvin on 1 Corinthians 3:21

21. Therefore let no man glory in men As there is nothing that is more vain than man, how little security there is in leaning upon an evanescent shadow! Hence he infers with propriety from the preceding statement, that we must not glory in men, inasmuch as the Lord thus takes away from mankind universally every ground of glorying. At the same time this inference depends on the whole of the foregoing doctrine, as will appear ere long. For as we belong to Christ alone, it is with good reason that he teaches us, that any supremacy of man, by which the glory of Christ is impaired, involves sacrilege.