William Burkitt on John 21:2

Observe here, that after Christ was crucified, the disciples returned for a time to their trade and employment of fishing; though they were called to be fishers of men, yet churches not being gathered and constituted at present, nor being able to maintain them, they labour with their hands to supply their present necessities.

Afterwards, when at the feast of Pentecost they had received those visible gifts of the Holy Ghost, which did furnish them for preaching the gospel to all nations, and they went forth to plant and propagate the gospel, we may believe they then gave over the labour of their secular callings, and applied themselves wholly to the work of the ministry. That may be done (Ecclesia constituenda) in a church which is constituting, or about to be constituted.

Observe farther, how Peter, with the rest, toil all night, and catch nothing; but no sooner is Christ come among them, but they inclose a multitude of fishes.

Thereby teaching us, that all human labours and endeavours are in vain, unless Christ by his presence and blessing crown them with success.