Matthew Henry: Authority and The Keys
It is the power of the keys that is given, alluding to the custom of investing men with authority in such a place, by delivering to them the keys of the place. Or as the master of the house gives the keys to the steward, the keys of the stores where the provisions are kept, that he may give to every one in the house his portion of meat in due season (Luk_12:42), and deny it as there is occasion, according to the rules of the family. Ministers are stewards, 1Co_4:1; Tit_1:7. Eliakim, who had the key of the house of David, was over the household, Isa_22:22.
3. It is a power to bind and loose, that is (following the metaphor of the keys), to shut and open. Joseph, who was lord of Pharaoh’s house, and steward of the stores, had power to bind his princes, and to teach his senators wisdom, Psa_105:21, Psa_105:22. When the stores and treasures of the house are shut up from any, they are bound, interdico tibi aquâ et igne – I forbid thee the use of fire and water; when they are opened to them again, they are loosed from that bond, are discharged from the censure, and restored to their liberty.
4. It is a power which Christ has promised to own the due administration of; he will ratify the sentences of his stewards with his own approbation; It shall be bound in heaven, and loosed in heaven: not that Christ hath hereby obliged himself to confirm all church-censures, right or wrong; but such as are duly passed according to the word, clave non errante – the key turning the right way, such are sealed in heaven; that is, the word of the gospel, in the mouth of faithful ministers, is to be looked upon, not as the word of man, but as the word of God, and to be received accordingly, 1Th_2:13; Joh_12:20.