John Wesley on Revelation 3:7

The holy one, the true one - Two great and glorious names He that hath the key of David - A master of a family, or a prince, has one or more keys, wherewith he can open and shut all the doors of his house or palace. So had David a key, a token of right and sovereignty, which was afterward adjudged to Eliakim, Isaiah 22:22. Much more has Christ, the Son of David, the key of the spiritual city of David, the New Jerusalem; the supreme right, power, and authority, as in his own house. He openeth this to all that overcome, and none shutteth: he shutteth it against all the fearful, and none openeth. Likewise when he openeth a door on earth for his works or his servants, none can shut; and when he shutteth against whatever would hurt or defile, none can open.