John Calvin Commentary Matthew 21:44

"And he that falleth on this stone shall be broken to pieces: but on whomsoever it shall fall, it will scatter him as dust." — Matthew 21:44 (ASV)

And he who shall fall on this stone. Christ confirms more fully the former statement: he suffers no loss or diminution when he is rejected by the wicked. For even though their obstinacy were like a stone or like iron, yet by his own hardness he will break them, and therefore he will be even more highly glorified in their destruction. He perceived an astonishing obstinacy in the Jews, and therefore it was necessary that this kind of punishment should be described to them in an alarming manner, so that they might not flatter themselves while they dashed themselves against him in this way. This doctrine partly instructs us to give ourselves up gently, with a mild and tractable heart, to the dominion of Christ, and partly fortifies us against the obstinacy and furious attacks of the wicked, for whom a dreadful end awaits.

Those persons are said to fall upon Christ who rush forward to destroy him; not because they occupy a more elevated position than he does, but because their madness carries them so far that they endeavor to attack Christ as if he were below them. But Christ tells them that all that they will gain by it is that by the very conflict they will be broken. But when they have proudly exalted themselves in this way, he tells them that another thing will happen: they will be bruised under the stone, against which they so insolently dashed themselves.