Adam Clarke on Luke 19:40

If these should hold their peace, the stones would - cry out - Of such importance is my present conduct to you and to others, being expressly predicted by one of your own prophets, Zac 9:9, as pointing out the triumph of humility over pride, and of meekness over rage and malice, as signifying the salvation which I bring to the lost souls of men, that, if this multitude were silent, God would give even to the stones a voice, that the advent of the Messiah might be duly celebrated.