18While walking by the Sea of Galilee, he saw two brothers, Simon (who is called Peter) and Andrew his brother, casting a net into the sea, for they were fishermen.
We see Simon being called Peter in Matthew 16:18. He pronounces (on behalf of the other disciples) the first profession of faith. On this rock, Christ will build his church.
18 While walking by the Sea of Galilee, he saw two brothers, Simon (who is called Peter) and Andrew his brother, casting a net into the sea, for they were fishermen.