Here is, 1. The disrespect which Christ's kindred, according to the flesh, showed to him, when he was preaching (and they knew very well that he was then in his element); they not only stood without, having no desire to come in, and hear him, but they sent in a message to call him out to them (Mar 3:31, Mar 3:32), as if he must leave his work, to hearken to their impertinences; it is probable that they had no business with him, only sent for him on purpose to oblige him to break off, lest he should kill himself. He knew how far his strength would go, and preferred the salvation of souls before his own life, and soon after made it to appear with a witness; it was therefore an idle thing for them, under pretence of his sparing himself, to interrupt him; and it was worse, if really they had business with him, when they knew he preferred his business, as a Saviour, so much before any other business.
2. The respect which Christ showed to his spiritual kindred upon this occasion. Now, as at other times, he put a comparative neglect upon his mother, which seemed purposely designed to obviate the prevent the extravagant respect which men in aftertimes would be apt to pay her. Our respect ought to be guided and governed by Christ's; now the virgin Mary, or Christ's mother, is not equalled with, but postponed to, ordinary believers, on whom Christ here puts a superlative honour. He looked upon those that at about him, and pronounced those of them that not only heard, but did, the will of God, to be to him as his brother, and sister, and mother; as much esteemed, loved, and cared for, as his nearest relations, Mar 3:33-35. This is a good reason why we should honour those that fear the Lord, and choose them for our people; why we should be not hearers of the word only, but doers of the work, that we may share with the saints in this honour, Surely it is good to be akin to those who are thus nearly allied to Christ, and to have fellowship with those that have fellowship with Christ; and woe to those that hate and persecute Christ's kindred, that are his bone and his flesh, every one resembling the children of a king (see Jdg 8:18, Jdg 8:19); for he will with jealously plead their cause, and avenge their blood.

His brethren and his mother - Or rather, his mother and his brethren. This is the arrangement of the best and most ancient MSS.; and this clause, και αἱ αδελφαι σου, and thy sisters, Mar 3:32, should be Added, on the authority of ADEFGMSUV, fifty-five others, some editions, the margin of the later Syriac, Slavonic, Gothic, and all the Itala except four. Griesbach has received this reading into the text.
Calling him - This clause is wanting in one copy of the Itala. The Codex Alexandrinus has ζητουντες αυτον, seeking him.

For whosoever shall do the will of God,.... By believing in Christ, receiving him as a Saviour and Redeemer, and submitting to him in all his ordinances, as King of saints:

the same is my brother, and my sister, and my mother: such are openly, and manifestly related to Christ in a spiritual sense; and are as dear to him, and more so, than such persons are who stand in such a relation to others, or did to him according to the flesh. And this shows not only the near relation, and strong affection which Christ has for his people, but that he is not ashamed of them; and it may be concluded, that he will resent, in the keenest manner, every injury that is done them; See Gill on Mat 12:50.

Next: Mark Chapter 4