John 3:33

He who has received his witness has set his seal to this, that God is true.

John 6:27

Don't work for the food which perishes, but for the food which remains to eternal life, which the Son of Man will give to you. For God the Father has sealed him."

Romans 3:3-4

For what if some were without faith? Will their lack of faith nullify the faithfulness of God?

Romans 4:18-21

Who in hope believed against hope, to the end that he might become a father of many nations, according to that which had been spoken, "So will your seed be."

2 Corinthians 1:18

But as God is faithful, our word toward you was not "Yes and no."

2 Corinthians 1:22

who also sealed us, and gave us the down payment of the Spirit in our hearts.

Ephesians 1:13

in whom you also, having heard the word of the truth, the Good News of your salvation -- in whom, having also believed, you were sealed with the Holy Spirit of promise,

Titus 1:1-2

Paul, a servant of God, and an apostle of Jesus Christ, according to the faith of God's chosen ones, and the knowledge of the truth which is according to godliness,

Hebrews 6:17

In this way God, being determined to show more abundantly to the heirs of the promise the immutability of his counsel, interposed with an oath;

1 John 5:9-10

If we receive the witness of men, the witness of God is greater; for this is God's testimony which he has testified concerning his Son.

Revelation 7:3-8

saying, "Don't harm the earth, neither the sea, nor the trees, until we have sealed the bondservants of our God on their foreheads!"

Treasury of Scripture Knowledge

Summary

He that hath received his testimony hath set to his seal that God is true.

Bible References

Hath set

Romans 3:3
For what if some were without faith? Will their lack of faith nullify the faithfulness of God?
Romans 4:18
Who in hope believed against hope, to the end that he might become a father of many nations, according to that which had been spoken, "So will your seed be."
2 Corinthians 1:18
But as God is faithful, our word toward you was not "Yes and no."
Titus 1:1
Paul, a servant of God, and an apostle of Jesus Christ, according to the faith of God's chosen ones, and the knowledge of the truth which is according to godliness,
Hebrews 6:17
In this way God, being determined to show more abundantly to the heirs of the promise the immutability of his counsel, interposed with an oath;
1 John 5:9
If we receive the witness of men, the witness of God is greater; for this is God's testimony which he has testified concerning his Son.