A.T. Robertson Commentary Matthew 4:18

"And walking by the sea of Galilee, he saw two brethren, Simon who is called Peter, and Andrew his brother, casting a net into the sea; for they were fishers." — Matthew 4:18 (ASV)

Casting a net into the sea (βαλλαντας αμφιβληστρον εις την θαλασσαν). The word here for net is a casting-net (compare αμφιβαλλω in Mr 1:16, casting on both sides). The net was thrown over the shoulder and spread into a circle (αμφ). In 4:20 and 4:21 another word occurs for nets (δικτυα), a word used for nets of any kind. The large drag-(σαγηνη) appears in Mt 13:47.