Romans 8:16

So that the Spirit itself beareth witness with our spirit, that we are the children of God.

2 Corinthians 1:22

and given us the earnest of the Spirit in our hearts.

2 Corinthians 5:5

Now He, that hath wrought us hereunto, is God; who hath also given us the earnest of the Spirit.

Ephesians 1:13

In whom ye also trusted, when ye heard the word of truth, the gospel of your salvation: in whom also when ye believed, ye were sealed with the holy Spirit of promise,

2 Corinthians 1:12

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

Ephesians 4:30

And grieve not the holy Spirit of God whereby ye are sealed to 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

By this we know that we are 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 witness in himself: he, that believeth not God, hath in effect made Him a liar, because he believed not the testimony which God hath testified of his Son.

Romans 8:23

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

Romans 8:26

And the Spirit likewise helpeth our infirmities: for we know not what we should pray for, as we ought: but the Spirit itself intercedes for us with unutterable groans.

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 others, but those also who have the first-fruits of the Spirit, even we ourselves groan within ourselves, waiting for the adoption, to wit the redemption of our body.
2 Corinthians 1:22
and given us the earnest of the Spirit in our hearts.
2 Corinthians 5:5
Now He, that hath wrought us hereunto, is God; who hath also given us the earnest of the Spirit.
Ephesians 1:13
In whom ye also trusted, when ye heard the word of truth, the gospel of your salvation: in whom also when ye believed, ye were sealed with the holy Spirit of promise,
Ephesians 4:30
And grieve not the holy Spirit of God whereby ye are sealed to the day of redemption.
1 John 4:13
By this we know that we are 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 pious sincerity, not with carnal wisdom, but by the grace of God, we have had our conversation in the world, and especially towards 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 witness in himself: he, that believeth not God, hath in effect made Him a liar, because he believed not the testimony which God hath testified of his Son.

General references

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