Matteo 4:22

And they immediately left the ship and their father, and followed Him.

This occurred in the same neighborhood as the event just recorded and in immediate conjunction with it, Luke 5:10. John had probably been among those that followed Jesus at the Jordan, John 1:35-40, and had, in the meantime, also told his older brother James of his wonderful experience.

Therefore, although they were busily engaged with the routine of their calling, and although the call of Jesus implied the severing of family ties, there was just as little hesitation on their part. The honor of serving their Lord, even in poverty and humility, outweighs any and all temporal considerations.