Both he and his brother Peter were fishermen by trade, hence the tradition that Jesus called them to be his disciples by saying that he will make them "fishers of men" (Greek: ἁλιεῖς ἀνθρώπων, halieis anthrōpōn).
Både han selv og hans bror var fiskere; deraf følger traditionen, at Jesus kaldte dem til disciple, idet han ville gøre dem til "menneskefiskere" (græsk ἁλιείς ἀνθρώπων, halieis anthropon) .