John 3:1-5 says:
1There was a man named Nicodemus. Nicodemus was one of the Pharisees. He was an important Jewish leader. 2One night Nicodemus came to Jesus. Nicodemus said, "Teacher, we know that you are a teacher sent from God. No person can do these miracles that you do without God's help."3Jesus answered, "I tell you the truth. A person must be born again. If a person is not born again, then that person cannot be in God's kingdom."4Nicodemus said, "But if a man is already old, how can he be born again? A person cannot enter his mother's body again! So a person cannot be born a second time!"5But Jesus answered, "I tell you the truth. A person must be born from water and the Spirit. If a person is not born from water and the Spirit, then he cannot enter God's kingdom. (Easy-to-Read Version)
King James Version:
1There was a man of the Pharisees, named Nicodemus, a ruler of the Jews: 2The 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. 3Jesus answered and said unto him, Verily, verily, I say unto thee, Except a man be born again, he cannot see the kingdom of God. 4Nicodemus 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? 5Jesus 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.