James and John were evidently repairing (Gr. katartizo) their nets after a night of fishing (cf. 1 Corinthians 1:10; 2 Corinthians 13:11). [source][source][source]
"In the Synoptics, unlike Paul"s epistles, Jesus" call is not necessarily effectual. But in this instance it was immediately obeyed." [1][source]
The disciples left their father as well as their fishing ( Matthew 4:22). [source][source][source]
"The call of God through Jesus is sovereign and absolute in its authority; the response of those who are called is to be both immediate and absolute, involving a complete break with old loyalties. The actual shape of this break with the past will undoubtedly vary from individual to individual, but that there must be a fundamental, radical reorientation of a person"s priorities is taken for granted." [2][source]