1 John 5:10

⁸ And there are three that bear witness in earth, the Spirit, and the water, and the blood: and these three agree in one.

⁹ If we receive the witness of men, the witness of God is greater: for this is the witness of God which he hath testified of his Son.

He that believeth on the Son of God hath the witness in himself: he that believeth not God hath made him a liar; because he believeth not the record that God gave of his Son.

¹¹ And this is the record, that God hath given to us eternal life, and this life is in his Son.

¹² He that hath the Son hath life; and he that hath not the Son of God hath not life.

Do read the surrounding verses too, because the context often says more than a single verse.

Compare

BSB: Whoever believes in the Son of God has this testimony within him; whoever does not believe God has made Him out to be a liar, because he has not believed in the testimony that God has given about His Son.
KJV: He that believeth on the Son of God hath the witness in himself: he that believeth not God hath made him a liar; because he believeth not the record that God gave of his Son.
WEB: He who believes in the Son of God has the testimony in himself. He who doesn’t believe God has made him a liar, because he has not believed in the testimony that God has given concerning his Son.
ASV: He that believeth on the Son of God hath the witness in him: he that believeth not God hath made him a liar; because he hath not believed in the witness that God hath borne concerning his Son.
DARBY: He that believes on the Son of God has the witness in himself; he that does not believe God has made him a liar, because he has not believed in the witness which God has witnessed concerning his Son.
BLB: The one believing in the Son of God has the testimony in himself; the one not believing God has made Him a liar, because he has not believed in the testimony that God has testified concerning His Son.

ÅB: Den som tror på Guds Sønn, har vitnesbyrdet i seg selv; den som ikke tror Gud, har gjort ham til en løgner; for han har ikke trodd på det vitnesbyrd som Gud har vitnet om sin Sønn.
OTB: Den som tror på Guds Sønn har vitnesbyrdet i seg; den som ikke tror Gud har gjort Ham til en løgner, fordi han ikke har trodd på vitnesbyrdet som Gud har gitt om Sin Sønn.
B1930: Den som tror på Guds Sønn, har vidnesbyrdet i sig selv; den som ikke tror Gud, har gjort ham til en løgner; for han har ikke trodd på det vidnesbyrd som Gud har vidnet om sin Sønn.

Study notes (Tyndale)

Original text and word study

Cross references

Romans 8:16
The Spirit itself beareth witness with our spirit, that we are the children of God:
Read in context
Galatians 4:6
And because ye are sons, God hath sent forth the Spirit of his Son into your hearts, crying, Abba, Father.
Read in context
John 3:33
He that hath received his testimony hath set to his seal that God is true.
Read in context
John 5:38
And ye have not his word abiding in you: for whom he hath sent, him ye believe not.
Read in context
Hebrews 3:12
Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God.
Read in context
1 John 5:1
Whosoever believeth that Jesus is the Christ is born of God: and every one that loveth him that begat loveth him also that is begotten of him.
Read in context
Colossians 3:3
For ye are dead, and your life is hid with Christ in God.
Read in context
Numbers 23:19
God is not a man, that he should lie; neither the son of man, that he should repent: hath he said, and shall he not do it? or hath he spoken, and shall he not make it good?
Read in context