And this is the promise that He Himself made to us: eternal life.

John 3:15
that everyone who believes in Him may have eternal life.

John 6:40
For it is My Father's will that everyone who looks to the Son and believes in Him shall have eternal life, and I will raise him up at the last day."

John 10:28
I give them eternal life, and they will never perish. No one can snatch them out of My hand.

1 John 1:2
And this is the life that was revealed; we have seen it and testified to it, and we proclaim to you the eternal life that was with the Father and was revealed to us.

1 John 5:11
And this is that testimony: God has given us eternal life, and this life is in His Son.

1 John 5:13
I have written these things to you who believe in the name of the Son of God, so that you may know that you have eternal life.

And this is the promise that he has promised us, even eternal life.