Romans 8:16

The same Spirit beareth witness with our spirits, that we are the children of God.

2 Corinthians 1:22

Who hath also sealed us, and given us the earnest of the Spirit in our hearts.

2 Corinthians 5:5

Now he that hath wrought us to this very thing is God, who hath also given us the earnest of the Spirit.

Ephesians 1:13

In whom ye likewise believed, after ye had heard the word of truth, the gospel of your salvation; in whom having believed, ye were also sealed by that Holy Spirit of promise,

2 Corinthians 1:12

For this is our rejoicing, the testimony of our conscience, that in simplicity and godly sincerity, not with carnal wisdom, but by the grace of God, we have had our conversation in the world, and more especially toward you.

Ephesians 4:30

And grieve not the Holy Spirit of God, whereby ye are sealed unto the day of redemption.

1 John 3:19-22

And hereby we know that we are of the truth, and shall assure our hearts before him.

1 John 4:13

Hereby we know that we abide in him, and he in us, because he hath given us of his Spirit.

1 John 5:10

He that believeth on the Son of God, hath the testimony in himself. He that believeth not God, hath made him a liar, because he believeth not the testimony which he hath testified of his Son.

Romans 8:23

And not only they, but even we ourselves, who have the first-fruits of the Spirit, even we ourselves groan within ourselves, waiting for the adoption, the redemption of our body.

Romans 8:26

Likewise the Spirit also helpeth our infirmities: for we know not what we should pray for as we ought; but the Spirit itself maketh intercession for us, with groanings which cannot be uttered.

Treasury of Scripture Knowledge

Summary

The Spirit itself beareth witness with our spirit, that we are the children of God:

General references

Bible References

Spirit

Romans 8:23
And not only they, but even we ourselves, who have the first-fruits of the Spirit, even we ourselves groan within ourselves, waiting for the adoption, the redemption of our body.
2 Corinthians 1:22
Who hath also sealed us, and given us the earnest of the Spirit in our hearts.
2 Corinthians 5:5
Now he that hath wrought us to this very thing is God, who hath also given us the earnest of the Spirit.
Ephesians 1:13
In whom ye likewise believed, after ye had heard the word of truth, the gospel of your salvation; in whom having believed, ye were also sealed by that Holy Spirit of promise,
Ephesians 4:30
And grieve not the Holy Spirit of God, whereby ye are sealed unto the day of redemption.
1 John 4:13
Hereby we know that we abide in him, and he in us, because he hath given us of his Spirit.

With our

2 Corinthians 1:12
For this is our rejoicing, the testimony of our conscience, that in simplicity and godly sincerity, not with carnal wisdom, but by the grace of God, we have had our conversation in the world, and more especially toward you.
1 John 3:19
And hereby we know that we are of the truth, and shall assure our hearts before him.
1 John 5:10
He that believeth on the Son of God, hath the testimony in himself. He that believeth not God, hath made him a liar, because he believeth not the testimony which he hath testified of his Son.

General references

Galatians 3:26
For ye are all sons of God by faith in Jesus Christ.