2 And I saw another angel coming up from the east, carrying the seal of the living God. And he shouted to those four angels, who had been given power to harm land and sea, 3 "Wait! Don't harm the land or the sea or the trees until we have placed the seal of God on the foreheads of his servants." 4 And I heard how many were marked with the seal of God-144,000 were sealed from all the tribes of Israel:
Matthew Henry's Commentary on Revelation 7:2-4
Commentary on Revelation 7:1-8
(Read Revelation 7:1-8)
In the figurative language of Scripture, the blowing of the four winds together, means a dreadful and general destruction. But the destruction is delayed. Seals were used to mark for each person his own possessions. This mark is the witness of the Holy Ghost, printed in the hearts of believers. And the Lord would not suffer his people to be afflicted before they were marked, that they might be prepared against all conflicts. And, observe, of those who are thus sealed by the Spirit, the seal must be on the forehead, plainly to be seen alike by friends and foes, but not by the believer himself, except as he looks stedfastly in the glass of God's word. The number of those who were sealed, may be understood to stand for the remnant of people which God reserved. Though the church of God is but a little flock, in comparison with the wicked world, yet it is a society really large, and to be still more enlarged. Here the universal church is figured under the type of Israel.