Luke 20:17
And he beheld them, and said, What is this then that is written, The stone which the builders rejected, the same is become the head of the corner?
And he beheld them,.... Looked very earnestly and wistly at them, speaking as it were by his looks, signifying, that verily so it would be, as he had said; that they would reject the Messiah, and put him to death, and bring utter ruin upon themselves, and deprive their posterity of many advantages and privileges:
and said, What is this then that is written; that is, what else is the meaning of such a Scripture? is not the sense of that perfectly agreeable to what has been said, that the Messiah shall be rejected by the principal men among the Jews in church and state, and yet he shall be exalted, who will then take vengeance on them?
The stone which the builders rejected, the same is become the head of the corner? The passage is in Ps 118:22.
See Gill on "Matthew 21:42".