Romans 8:16

The Spirit Himself testifieth with our spirit, that we are children of God;

2 Corinthians 1:22

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

2 Corinthians 5:5

Now He Who wrought us for this very thing is God, Who gave to us the earnest of the Spirit.

Ephesians 1:13

in Whom ye also??fter having heard the word of the truth, the Gospel of your salvation, in Whom having also believed??ere sealed with the Holy Spirit of promise,

2 Corinthians 1:12

For our glorying is this, the testimony of our conscience, that in holiness and sincerity of God, not in fleshly wisdom, but in the grace of God, we behaved ourselves in the world, and more abundantly toward you.

Ephesians 4:30

And grieve not the Holy Spirit of God, in Whom ye were sealed unto the day of redemption.

1 John 3:19-22

Hereby we shall know that we are of the truth, and we shall assure our heart before Him;

1 John 4:13

In this 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 believes on the Son of God has the witness in himself; he that believes not God has made Him a liar; because he has not believed in the testimony that God testified concerning His Son.

Romans 8:23

and, not only so, but ourselves also, who have the first fruit of the Spirit, even we ourselves are groaning within ourselves, waiting for the adoption, the redemption of our body.

Romans 8:26

And, in like manner, the Spirit also helpeth our weakness; for we know not what to pray for as we ought; but the Spirit Himself 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 so, but ourselves also, who have the first fruit of the Spirit, even we ourselves are groaning within ourselves, waiting for the adoption, the redemption of our body.
2 Corinthians 1:22
Who also sealed us, and gave us the earnest of the Spirit in our hearts.
2 Corinthians 5:5
Now He Who wrought us for this very thing is God, Who gave to us the earnest of the Spirit.
Ephesians 1:13
in Whom ye also??fter having heard the word of the truth, the Gospel of your salvation, in Whom having also believed??ere sealed with the Holy Spirit of promise,
Ephesians 4:30
And grieve not the Holy Spirit of God, in Whom ye were sealed unto the day of redemption.
1 John 4:13
In this 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 our glorying is this, the testimony of our conscience, that in holiness and sincerity of God, not in fleshly wisdom, but in the grace of God, we behaved ourselves in the world, and more abundantly toward you.
1 John 3:19
Hereby we shall know that we are of the truth, and we shall assure our heart before Him;
1 John 5:10
He that believes on the Son of God has the witness in himself; he that believes not God has made Him a liar; because he has not believed in the testimony that God testified concerning His Son.

General references

Galatians 3:26
for ye are all sons of God through faith in Christ Jesus;