This Bible contradiction is from the Skeptic's Annotated Bible.
God revealed it to him; no human told him.
Matthew 16:16-17 View context
And Simon Peter answered and said, Thou art the Christ, the Son of the living God.
And Jesus answered and said unto him, Blessed art thou, Simon Bar-jona: for flesh and blood hath not revealed [it] unto thee, but my Father which is in heaven.
His brother Andrew told him.
John 1:40-41 View context
One of the two which heard John [speak], and followed him, was Andrew, Simon Peter's brother.
He first findeth his own brother Simon, and saith unto him, We have found the Messias, which is, being interpreted, the Christ.