Matthew 4:18

When Christ began to preach, he began to gather disciples, who should now be the hearers, and hereafter the preachers, of his doctrine, who should now be witnesses of his miracles, and hereafter concerning them. Now, in these verses, we have an account of the first disciples that he called into fellowship with himself. And this was an instance, 1. Of effectual calling to Christ. In all his preaching he gave a common call to all the country, but in this he gave a special and particular call to those that were given him by the Father. Let us see and admire the power of Christ's grace, own his word to be the rod of his strength, and wait upon him for those powerful influences which are necessary to the efficacy of the gospel call - those distinguishing influences. All the country was called, but these were called out, were redeemed from among them. Christ was so manifested to them, as he was not manifested unto the world. 2. It was an instance of ordination, and appointment to the work of the ministry. When Christ, as a Teacher, set up his great school, one of his first works was to appoint ushers, or under masters, to be employed in the work of instruction. Now he began to give gifts unto men, to put the treasure into earthen vessels. It was an early instance of his care for the church. Now we may observe here, I.

— Matthew Henry's Concise Commentary (public domain)

And Jesus, walking--The word "Jesus" here appears not to belong to the text, but to have been introduced from those portions of it which were transcribed to be used as church lessons; where it was naturally introduced as a connecting word at the commencement of a lesson. by the Sea of Galilee, saw two brethren, Simon called Peter and Andrew his brother, casting a net into the sea; for they were fishers--"called Peter" for the reason mentioned in Mat 16:18.

— Jamieson-Fausset-Brown Commentary (public domain)