Matthew 4:20

They straightway left their nets - A change, as far as it respected secular things, every way to their disadvantage. The proud and the profane may exult and say, "Such preachers as these cannot be much injured by their sacrifices of secular property - they have nothing but nets, etc., to leave." Let such carpers at the institution of Christ know, that he who has nothing but a net, and leaves that for the sake of doing good to the souls of men, leaves his All: besides, he lived comfortably by his net before; but, in becoming the servant of all for Christ's sake, he often exposes himself to the want of even a morsel of bread. See on Matthew 19:27 (note).

Straightway - Immediately - as all should do when the Lord Jesus calls them.

Left their nets - Their nets were the means of their living, perhaps all their property. By leaving them immediately, and following him, they gave every evidence of sincerity. They showed, what we should, that they were willing to forsake all for the sake of Jesus, and to follow him wherever he should lead them. They went forth to persecution and death for his sake; but also to the honor of saving souls from death, and establishing a church that shall continue to the end of time. Little did they know what awaited them when they left their unmended nets to rot on the beach, and followed the unknown and unhonored Jesus of Nazareth. So we know not what awaits us when we become his followers; but we should cheerfully go when our Saviour calls, willing to commit all into his hands - come honor or dishonor, sickness or health, riches or poverty, life or death. Be it ours to do our duty at once, and to commit the result to the great Redeemer who has called us. Compare Matthew 6:33; Matthew 8:21-22; John 21:21-22.

Follow him - This is an expression denoting that they became his disciples, 2 Kings 6:19.