When Jesus had heard. These words appear to be at variance with the narrative of the Evangelist John, who declares, that John and Christ discharged the office of public teachers at the same time. But we have to observe, that our three Evangelists pass over in silence that short space of time, because John's course was not yet completed, and because that course was intended to be a preparation for receiving the Gospel of Christ. And, in point of fact, though Christ discharged the office of teacher within that period, he did not, strictly speaking, begin to preach the Gospel, till he succeeded to John. Most properly, therefore, do the three Evangelists admit and declare, that the period, during which John prepared disciples for Christ, belonged to his ministry: for it amounts to this, that, when the dawn was passed, the sun arose. It is proper to observe the mode of expression employed by Luke, that Jesus came in the power, or, by the power, of the Spirit into Galilee: for it is of great consequence, that we do not imagine Christ to have any thing about him that is earthly or human, but that our minds be always occupied, and our feelings affected by his heavenly and divine power.

John was cast into prison - For an account of the imprisonment of John see Matthew 14:1-13.
He departed into Galilee - See Matthew 2:22. The reasons why Jesus then went into Galilee were probably:
1. Because the attention of the people had been much excited by John's preaching, and things seemed to be favorable for success in his own ministry.
2. It appeared desirable to have some one to second John in the work of reformation.
3. It was less dangerous for him to commence his labors there than near Jerusalem. Judea was under the dominion of the scribes, and Pharisees, and priests. They would naturally look with envy on any one who set himself up for a public teacher, and who should attract much attention there. It was important, therefore, that the work of Jesus should begin in Galilee, and become somewhat established and known before he went to Jerusalem.

(2) Now when Jesus had heard that John was cast into prison, he departed into Galilee;
(2) When the Herald's mouth is stopped, the Lord reveals himself and brings full light into the darkness of this world, preaching free forgiveness of sins for those that repent.

Now, when Jesus had heard that John was cast into prison,.... John was cast into prison by Herod; the reason of it may be seen in Matthew 14:3. The prison into which he was cast, according to Josephus (s), was the castle of Machaeras: here he continued some time before he was put to death; for from hence he sent two disciples to Jesus, to know if he was the Messiah, Matthew 11:2. Now when Jesus heard of this his imprisonment,
he departed into Galilee; not so much on account of safety, or for fear of Herod, but to call his disciples, who lived in that country.
(s) Antiq. l. 18. c. 7.

It is just with God to take the gospel and the means of grace, from those that slight them and thrust them away. Christ will not stay long where he is not welcome. Those who are without Christ, are in the dark. They were sitting in this condition, a contented posture; they chose it rather than light; they were willingly ignorant. When the gospel comes, light comes; when it comes to any place, when it comes to any soul, it makes day there. Light discovers and directs; so does the gospel. The doctrine of repentance is right gospel doctrine. Not only the austere John Baptist, but the gracious Jesus, preached repentance. There is still the same reason to do so. The kingdom of heaven was not reckoned to be fully come, till the pouring out of the Holy Spirit after Christ's ascension.

CHRIST BEGINS HIS GALILEAN MINISTRY--CALLING OF PETER AND ANDREW, JAMES AND JOHN--HIS FIRST GALILEAN CIRCUIT. ( = Mark 1:14-20, Mark 1:35-39; Luke 4:14-15). (Matthew 4:12-25)
Now when Jesus had heard that John was cast into prison--more simply, "was delivered up," as recorded in Matthew 14:3-5; Mark 6:17-20; Luke 3:19-20.
he departed--rather, "withdrew."
into Galilee--as recorded, in its proper place, in John 4:1-3.

Now when he heard that John was delivered up. A long period lapses between the temptation and the next event recorded. Matthew does not try to follow the order of events, and he now passes over more than a year. This year had been actively employed. The intervening events are, (1) the return of Jesus from the wilderness to Bethabara, where the first disciples are called (John 1:15-37); (2) the return to Galilee and the miracle at Cana (John 2:1-11); (3) the first passover of the Lord's ministry in Jerusalem and the temple cleansed (John 2:14-25); (4) interview with Nicodemus (John 3:1-21); (5) ministry in Judea (John 4:3); (6) leaves for Galilee, passes through Samaria, conversation at Sychar (John 4:4-42); (7) heals nobleman's son (John 4:46-54); (8) a period of retirement in Galilee, John imprisoned (Matthew 4:12); (9) attends feast in Jerusalem, miracle at pool of Bethesda (John 5); (10) returns to Galilee, April A. D. 28. We thus see that an interval of more than a year elapsed between the temptation and the imprisonment of John. John was thrown into prison because he rebuked Herod (Matthew 14:4; Mark 6:17).
Withdrew into Galilee. From prudence (John 4:1). Christ had been teaching in Judea (John 4:2).

He retired into Galilee - This journey was not immediately after his temptation. He first went from Judea into Galilee, John 1:43; John 2:1. Then into Judea again, and celebrated the passover at Jerusalem, John 2:13. He baptized in Judea while John was baptizing at Enon, John 3:22-23. All this time John was at liberty, John 3:24. But the Pharisees being offended, John 4:1; and John put in prison, he then took this journey into Galilee. Mark 1:14.