Jamieson, Fausset and Brown on John 3:25-26

25-26. between some of--rather, "on the part of."

and the Jews--rather (according to the best manuscripts), "and a Jew,"

about purifying--that is, baptizing, the symbolical meaning of washing with water being put (as in Joh 2:6) for the act itself. As John and Jesus were the only teachers who baptized Jews, discussions might easily arise between the Baptist's disciples and such Jews as declined to submit to that rite.