Andrew, Simon Peter's brother, was one of the two who heard John's testimony and followed Jesus.

Matthew 4:18
As Jesus was walking beside the Sea of Galilee, He saw two brothers, Simon called Peter and his brother Andrew. They were casting a net into the sea, for they were fishermen.

Mark 1:16
As Jesus was walking beside the Sea of Galilee, He saw Simon and his brother Andrew. They were casting a net into the sea, for they were fishermen.

Luke 5:1
On one occasion, while Jesus was standing by the Lake of Gennesaret with the crowd pressing in on Him to hear the word of God,

Luke 5:2
He saw two boats at the edge of the lake. The fishermen had left them and were washing their nets.

John 1:39
"Come and see," He replied. So they went and saw where He was staying, and spent that day with Him. It was about the tenth hour.

John 2:2
and Jesus and His disciples had also been invited to the wedding.

John 4:33
So the disciples asked one another, "Could someone have brought Him food?"

John 6:8
One of His disciples, Andrew, Simon Peter's brother, said to Him,

One of the two which heard John speak, and followed him, was Andrew, Simon Peter's brother.