2 Now when the Lord knew this, “when He had heard that the Pharisees had learned that He was making more disciples than John, and baptized more (though Jesus baptized not, but His disciples), He left Judea, and departed again into Galilee.” We must not discourse of this too long, lest, by dwelling on what is manifest, we shall lack the time to investigate and lay open what is obscure. Certainly, if the Lord saw that the fact of their coming to know that He made more disciples, and baptized more, would so avail to salvation to the Pharisees in following Him, as to become themselves His disciples, and to desire to be baptized by Him; rather would He not have left Judea, but would have remained there for their sakes.
But because He knew their knowledge of the fact, and at the same time knew their envy, and that they learned this, not to follow, but to persecute him, He departed thence. He could, indeed, even when present, cause that He should not be taken of them, if He would not; He had it in His power not to be put to death, if He would not, since He had the power not to be born, if He would not. But because, in everything that He did as man, He was showing an example to them who were to believe in Him (that any one servant of God sins not if he retire into another place, when he sees, it may be, the rage of his persecutors, or of them that seek to bring his soul into evil; but if a servant of God did this he might appear to commit sin, had not the Lord led the way in doing it), that good Master did this to teach us, not because He feared it.
Source: Tractates on the Gospel of John (New Advent)