And to the angel of the church in Philadelphia write; These things saith He that is holy, He that is true, He that hath the key of David, He that openeth, and no man shutteth; and shutteth, and no man openeth. – Revelation 3:7

He is the King of grace: He gives, or He withholds. The river of God’s mercy flows from underneath His throne; He sits as Sovereign in the dispensation of mercy. He hath the key of heaven; He openeth, and no man shutteth; He shutteth, and no man openeth; He calleth, and the stubborn heart obeys; He willeth, and the rebellious spirit bends its knee; for He is Master of men, and when He wills to bless, none can refuse the benediction. He reigneth in His church amidst willing spirits; and He reigns for His church over all the nations of the world, that He may gather unto Himself a people that no man can number who shall bow before the scepter of His love.

I pause here, overcome by the majesty of the subject, and instead of attempting to describe that brow, and those glittering crowns, I shall act the part of a seraph, and bow before that well-crowned head, and cry, “Holy, holy, holy, art Thou Lord God of hosts! The keys of heaven, and death, and hell, hang at Thy girdle; Thou art supreme, and unto Thee be glory for ever and ever.”~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/0281.cfm