Mark 3:21 - Ellicott's Commentary On The Whole Bible

And when his friends ... — Literally, those from Him — i.e., from His home. As the “mother and the brethren” are mentioned later on in the chapter as coming to check His teaching, we must see in these some whom they had sent with the same object. To them the new course of action on which our Lord had entered seemed a sign of over-excitement, recklessly rushing into danger. We may, perhaps, see in the random word thus uttered that which gave occasion to the more malignant taunt of the scribes in the next verse. They were saying now, as they said afterwards (John 10:20), “He hath a devil, and is mad.”