The Sealing

Daniel 9:24 Seventy weeks are determined upon thy people and upon thy holy city, to finish the transgression, and to make an end of sins, and to make reconciliation for iniquity, and to bring in everlasting righteousness, and to seal up the vision and prophecy, and to anoint the most Holy.

Gill:  and to seal up the vision and prophecy; not to shut it up out of sight; rather to set a mark on it, by which it might be more clearly known

John 3:33 He that hath received his testimony hath set to his seal that God is true.

Gill: hath set to his seal that God is true; faithful in fulfilling the promises he has made concerning the Messiah, and his coming: he firmly believes that God is true to every word of his, and will make good every promise; and this he seals, ratifies, and confirms by his embracing the testimony of Christ; whereas, on the contrary, he that believes not makes God a liar, than which, nothing can be more reproachful to him, #1Jo 5:10. The Jews have a saying {z} that "the seal of the blessed God is truth". The Arabic version renders it, "he is already sealed, because God is true"; and the Ethiopic version, "God hath sealed him, because he is true"; namely, with his holy Spirit; see #2Co 1:22 Eph 1:13 4:30.

John 6:27 Labour not for the meat which perisheth, but for that meat which endureth unto everlasting life, which the Son of man shall give unto you: for him hath God the Father sealed.

Gill:  for him hath God the Father sealed; designated and appointed to be the Saviour, and Redeemer of his people, and has sent, authorized, and commissioned him as such; and has made him known, and approved of him, by the descent of the Spirit on him, and by a voice from heaven, declaring him his beloved Son; and has confirmed him to be the Messiah by the miraculous works he gave him to finish; for all which several uses seals are, as to distinguish one thing from another, to render anything authentic, to point it out, or to confirm it.

2 Cor. 1:22 Who hath also sealed us, and given the earnest of the Spirit in our hearts.

Gill[S]ometimes a seal is used to certify, make sure, or assure the truth of a thing; see #Joh 3:33 1Co 9:3 Jer 33:10 in which sense the word "sealing" is used here, and intends that assurance which God gives his people of their interest in his love, and the covenant of grace; of their election of God, and redemption by Christ; of their interest in Christ, and union with him; of their justification by him, and adoption through him; of the truth of grace in their hearts, their perseverance in it, and sure and certain enjoyment of eternal glory.

Rev. 7:3 Saying, Hurt not the earth, neither the sea, nor the trees, till we have sealed the servants of our God in their foreheads.

Gill: [reference to the forehead] may be to #Eze 9:4, and shows, that though these persons were hid and concealed from men, they were well known to God and Christ

Ezek 9
1 ¶ He cried also in mine ears with a loud voice, saying, Cause them that have charge over the city to draw near, even every man with his destroying weapon in his hand.
2 And, behold, six men came from the way of the higher gate, which lieth toward the north, and every man a slaughter weapon in his hand; and one man among them was clothed with linen, with a writer’s inkhorn by his side: and they went in, and stood beside the brasen altar.
3 And the glory of the God of Israel was gone up from the cherub, whereupon he was, to the threshold of the house. And he called to the man clothed with linen, which had the writer’s inkhorn by his side;
4 And the LORD said unto him, Go through the midst of the city, through the midst of Jerusalem, and set a mark upon the foreheads of the men that sigh and that cry for all the abominations that be done in the midst thereof.
5 ¶ And to the others he said in mine hearing, Go ye after him through the city, and smite: let not your eye spare, neither have ye pity:
6 Slay utterly old and young, both maids, and little children, and women: but come not near any man upon whom is the mark; and begin at my sanctuary. Then they began at the ancient men which were before the house.
7 And he said unto them, Defile the house, and fill the courts with the slain: go ye forth. And they went forth, and slew in the city.
8 And it came to pass, while they were slaying them, and I was left, that I fell upon my face, and cried, and said, Ah Lord GOD! wilt thou destroy all the residue of Israel in thy pouring out of thy fury upon Jerusalem?
9 Then said he unto me, The iniquity of the house of Israel and Judah is exceeding great, and the land is full of blood, and the city full of perverseness: for they say, The LORD hath forsaken the earth, and the LORD seeth not.
10  And as for me also, mine eye shall not spare, neither will I have pity, but I will recompense their way upon their head.
11 And, behold, the man clothed with linen, which had the inkhorn by his side, reported the matter, saying, I have done as thou hast commanded me.

Eph. 4:
29 Let no corrupt communication proceed out of your mouth, but that which is good to the use of edifying, that it may minister grace unto the hearers.
30 And grieve not the holy Spirit of God, whereby ye are sealed unto the day of redemption.

Paul Bayne on Eph. 4:30:

To seal a thing is to mark it and distinguish it from other; John 6:27, “Him hath God the Father sealed.” It doth confirm things and make them authentical, as in all kind of instruments, they are blanks till the seal be passed.  ….

Daniel 12: 4 But thou, O Daniel, shut up the words, and seal the book, even to the time of the end: many shall run to and fro, and knowledge shall be increased.

Seiss:  [T]his shutting and sealing had reference to the authentication of the testimony and law of god as to the proper and only rule to which the people were to come for wisdom and direction; …. The securement to it of its true office, place and authority … give it authentically, and arrange for its perpetual preservation as an authoritative word from Heaven …  The idea of the angel was, that the whole matter was now complete, certified and true beyond all addition or change, and was so to be treated.  Just as valuable official documents intended to direct and inform successive generations are carefully engrossed and secured and held inviolable against all tampering; … that we might have them in all their authoritative certainty, be sure of their divine contents and fine in them a right knowledge of God’s revelations.