They asked him, Why baptizest thou then? — Without any commission from the sanhedrim? And not only heathens (who were always baptized before they were admitted to circumcision) but Jews also?
Related Commentaries of John 1:25
John 1:25
25 And they asked him, and said unto him, Why baptizest thou then, if thou be not that Christ, nor Elias, neither that prophet?