One of the two who heard John speak, and followed Him, was Andrew, Simon Peter's brother.
John 1:40
Surrounding context
1:39 He said to them, "Come and see." They came and saw where He was staying, and remained with Him that day (now it was about the tenth hour).
1:40 One of the two who heard John speak, and followed Him, was Andrew, Simon Peter's brother.
1:41 He first found his own brother Simon, and said to him, "We have found the Messiah" (which is translated, the Christ).