Mark 1:5
And there went out unto him all the land of Judaea, and they of Jerusalem, and were all baptized of him in the river of Jordan, confessing their sins.
And there went out unto him all the land of Judea,.... The people of the land, a great number of them:
and they of Jerusalem; the inhabitants of Jerusalem, hearing of this new preacher, the new doctrine that he taught, and the new ordinance that he administered:
and were all baptized of him in the river Jordan, confessing their sins; that is, as many of them as were brought to a sight and sense of their sins, and made a confession of them, these he baptized, or immersed, in the river Jordan; for certain it is, that there were many of the Pharisees and Sadducees who came, whom he rejected;
See Gill on "Matthew 3:5",
See Gill on "Matthew 3:6",
See Gill on "Matthew 3:7".