For both the One who sanctifies and those who are sanctified are of the same family. So Jesus is not ashamed to call them brothers.
11. For both he that sanctifieth, etc. He proves that it was necessary that what he had said should be fulfilled in the person of Christ on account of his connection with his members; and he also teaches that it was a remarkable evidence of the divine goodness that he put on our flesh.
Having mentioned the death of Christ, the apostle here proceeds to prevent and remove the scandal of the cross; and this he does by showing both how it became God that Christ should suffer and how much man should be benefited by those sufferings. I.
Commenting on Hebrews 2:10-13
Saying, I will declare thy name unto my brethren,.... These words, with the following clause, are cited from Psa 22:22 as a proof of what the apostle had before asserted; and that this psalm is to be understood, not of the Jewish nation, or people of Israel, nor of Esther, nor of David, but of the Messiah, appears from the title of it, "Aijeleth, Shahar"...