Romans 8:16

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

2 Corinthians 1:22

who also sealed us and gave us the Spirit in our hearts as a pledge.

2 Corinthians 5:5

Now He who prepared us for this very purpose is God, who gave to us the Spirit as a pledge.

Ephesians 1:13

In Him, you also, after listening to the message of truth, the gospel of your salvation—having also believed, you were sealed in Him with the Holy Spirit of promise,

2 Corinthians 1:12

For our proud confidence is this: the testimony of our conscience, that in holiness and godly sincerity, not in fleshly wisdom but in the grace of God, we have conducted ourselves in the world, and especially toward you.

Ephesians 4:30

Do not grieve the Holy Spirit of God, by whom you were sealed for the day of redemption.

1 John 3:19-22

We will know by this that we are of the truth, and will assure our heart before Him

1 John 4:13

By this we know that we abide in Him and He in us, because He has given us of His Spirit.

1 John 5:10

The one who believes in the Son of God has the testimony in himself; the one who does not believe God has made Him a liar, because he has not believed in the testimony that God has given concerning His Son.

Romans 8:23

And not only this, but also we ourselves, having the first fruits of the Spirit, even we ourselves groan within ourselves, waiting eagerly for our adoption as sons, the redemption of our body.

Romans 8:26

In the same way the Spirit also helps our weakness; for we do not know how to pray as we should, but the Spirit Himself intercedes for us with groanings too deep for words;

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 this, but also we ourselves, having the first fruits of the Spirit, even we ourselves groan within ourselves, waiting eagerly for our adoption as sons, the redemption of our body.
2 Corinthians 1:22
who also sealed us and gave us the Spirit in our hearts as a pledge.
2 Corinthians 5:5
Now He who prepared us for this very purpose is God, who gave to us the Spirit as a pledge.
Ephesians 1:13
In Him, you also, after listening to the message of truth, the gospel of your salvation—having also believed, you were sealed in Him with the Holy Spirit of promise,
Ephesians 4:30
Do not grieve the Holy Spirit of God, by whom you were sealed for the day of redemption.
1 John 4:13
By this we know that we abide in Him and He in us, because He has given us of His Spirit.

With our

2 Corinthians 1:12
For our proud confidence is this: the testimony of our conscience, that in holiness and godly sincerity, not in fleshly wisdom but in the grace of God, we have conducted ourselves in the world, and especially toward you.
1 John 3:19
We will know by this that we are of the truth, and will assure our heart before Him
1 John 5:10
The one who believes in the Son of God has the testimony in himself; the one who does not believe God has made Him a liar, because he has not believed in the testimony that God has given concerning His Son.

General references

Galatians 3:26
For you are all sons of God through faith in Christ Jesus.