Revelation 20:1

And I saw an angel come down from heaven
All Christ's enemies, and Satan's instruments being removed, the devil is left alone, and only stands in the way of Christ's kingdom; and what will be done to him, and how he will be in the issue disposed of, this vision gives an account: by the "angel" John saw, is not to be understood Constantine the great; for though he is the man child that was taken up to God, and his throne, being advanced to the empire, yet he cannot, with that propriety, be said to come down from heaven; and though he vanquished the Heathen emperors, in which the dragon presided, and cast Paganism out of the empire, by which the devil ruled in it, yet the binding of Satan is another kind of work, and seems too great for him; and besides, did not take place in his time, as will be seen hereafter: nor is an apostle, or a minister of the Gospel intended; such are indeed called angels in this book, and may be said to come down from heaven, because they have their commission from thence; and particularly the apostles had the keys of the kingdom of heaven, but not the key of the bottomless pit; and a chain and system of Gospel truths, which they made good use of for the establishing of Christ's kingdom, and weakening of Satan's, but not such a chain as is here meant; and they had the power of binding and loosing, or of declaring things lawful or unlawful, but not of binding and loosing of Satan; nor was he bound in the apostolic age: nor is one of the ministering spirits, or a deputation of angels designed; for though Christ will be revealed from heaven with his mighty angels, and will make use of them, both to gather together his elect, and to cast the wicked into the lake of fire, yet not to bind Satan; but the Lord Jesus Christ himself is this angel, who is the angel of God's presence, and of the covenant; and who is in this book called an angel, ( Revelation 7:2 ) ( 10:1 ) to whom all the characters here well agree, and to whom the work of binding Satan most properly belongs; for who so fit to do it, or so capable of it, as the seed of the woman, that has bruised serpent's head, or as the Son of God, who was manifested to destroy the works of the devil, yea, to destroy him himself; and who dispossessed multitudes of devils from the bodies of men, and is the strong man armed that dislodges Satan from the souls of men, and is the same with Michael, who drove him from heaven, and cast him out from thence before, ( Revelation 12:7 Revelation 12:8 ) . And his coming down from heaven is not to be understood of his incarnation, or of his coming from thence by the assumption of human nature; for Satan was not bound by him then, as will be seen hereafter; but of his second coming, which will be from heaven, where he now is, and will be local, visible, and personal: of no other coming of his does this book speak, as seen by John, or as future; nor will the order of this vision, after the ruin of the beast and false prophet, admit of any other.

Having the key of the bottomless pit:
the abyss or deep, the same out of which the beast ascended, ( Revelation 11:7 ) ( 17:8 ) . And the key of this becomes no hand so well as his who has the keys of hell and death, ( Revelation 1:18 ) who has all power in heaven and in earth, and has the power of hell, of opening and shutting it at his pleasure, which is signified by this phase; see ( Revelation 9:1 ) . The Ethiopic version reads, "the key of the sun", where some have thought hell to be; and yet the same version renders the word, the deep, in ( Revelation 20:3 ) .

And a great chain in his hand;
the key in one hand, and the chain in another; by which last is meant, not any material chain, with which spirits cannot be bound, nor indeed sometimes bodies possessed by evil spirits, ( Mark 5:3 Mark 5:4 ) but the almighty power of Christ, which he will now display in binding Satan faster and closer than ever.