on Matthew 21 :44
The 44th verse should certainly come before Matthew 21:43, otherwise the narration is not consecutive.
Matthew 21:42. The stone which the builders rejected, is become the head of the corner, etc. Matthew 21:44. Whosoever shall fall on this stone shall be broken, etc. This is an allusion to the punishment of stoning among the Jews. The place of stoning was twice as high as a man; while standing on this, one of the witnesses struck the culprit on the loins, so that he fell over this scaffold; if he died by the stroke and fall, well; if not, the other witness threw a stone upon his heart, and despatched him. That stone thrown on the culprit was, in some cases, as much as two men could lift up. Tract Sanhed. and Bab. Gemara, and Lightfoot. See also the note on John 8:7 (note).
He, whether Jew or Gentile, who shall not believe in the Son of God, shall suffer grievously in consequence; but on whomsoever the stone (Jesus Christ) falls in the way of judgment, he shall be ground to powder, λικμησει αυτον - it shall make him so small as to render him capable of being dispersed as chaff by the wind. This seems to allude, not only to the dreadful crushing of the Jewish state by the Romans, but also to that general dispersion of the Jews through all the nations of the world, which continues to the present day. This whole verse is wanting in the Codex Bezae, one other, five copies of the Itala, and Origen; but it is found in the parallel place, Luke 20:18, and seems to have been quoted from Isaiah 8:14, Isaiah 8:15. He shall be for a Stone of Stumbling, and for a Rock of Offence to both the houses of Israel - and many among them shall Stumble and Fall, and be Broken.
on Matthew 21 :44
Whosoever shall fall ... - There is a reference here, doubtless, to Isaiah 8:14-15. Having made an allusion to himself "as a stone," or a rock Matthew 21:42, he proceeds to state the consequences of coming in contact with it. He that falls upon it shall be broken; he that "runs against it" - a cornerstone, standing out from the other parts of the foundation shall be injured, or broken in his limbs or body. He that is offended with my being the foundation, or that opposes me, shall by the act injure himself, or make himself miserable "by so doing," even were there nothing further. But there is something further.
On whomsoever it shall fall, it will grind him to powder - That is, in the original, will reduce him to dust, so that it may be scattered by the winds. There is an allusion here, doubtless, to the custom of stoning as a punishment among the Jews. A scaffold was erected twice the height of the man to be stoned. Standing on its edge, he was violently struck off by one of the witnesses: if he died by the blow and the fall, nothing further was done; if not, a heavy stone was thrown down on him, which at once killed him. So the Saviour speaks of the "falling" of the stone on his enemies. They who oppose him, who reject him, and who continue impenitent, shall be crushed by him in the day of judgment, and perish forever.
on Matthew 21 :44
21:44 Whosoever shall fall on this stone shall be broken - Stumblers at Christ shall even then receive much hurt. He is said to fall on this stone, who hears the Gospel and does not believe. But on whomsoever it shall fall - In vengeance, it will utterly destroy him. It will fall on every unbeliever, when Christ cometh in the clouds of heaven. Luke 20:18.