John 3:1 (KJV)
There was a man of the Pharisees, named Nicodemus, a ruler of the Jews: 2 the same came to Jesus by night, and said unto him, Rabbi, we know that thou art a teacher come from God: for no man can do these miracles that thou doest, except God be with him.
3 Jesus answered and said unto him. Verily, verily I say unto thee, Except a man be born again, he cannot see the kingdom of God. 4 Nicodemus saith unto him, how can a man be born when he is old? Can he enter the second time into his mother’s womb, and be born?
5 Jesus answered, Verily, verily, I say unto thee, except a man be born of water and of the spirit, he cannot enter into the kingdom of God. 6 That which is born of the flesh in flesh and that which is born of the Spirit is Spirit. 7 Marvel not that I said unto thee, Ye must be born again. 8 The wind bloweth where it listeth, and thou hearest the sound thereof, but canst not tell whence it cometh, and whither it goeth: so is every one that is born of the Spirit. 9 Nicodemus answered and said unto him, How can these things be? 10 Jesus anwered and said unto him, Art thou a master of Israel, and knowest not these things?
11 Verily, verily, I say unto thee, We speak that we do know, and testify that we have seen: and ye receive not our witness. 12 If I have told you earthly things, and ye believe not, how shall ye believe, if I tell you of heavenly things? And no man hath ascended up to heaven, but he that come down from heaven, even the Son of man which is in Heaven.