(17) And he beheld them.--Better, He looked on them. The Greek verb implies the gaze turned and fixed on its object, in addition to the mere act of beholding.

Verses 17, 18. - And he beheld them, and said, What is this then thai; is written, The stone which the builders rejected, the same is become the head of the corner? Whosoever shall fall upon that stone shall be broken; but on whomsoever it shall fall, it will grind him to powder. In spite of the deprecating expression, the severity of the tone of Jesus increases in his next words, when, looking at them with grave anger (ἐμβλέψας), he proceeds to speak of himself under the figure of the rejected stone. Quoting a well-known psalm (Psalm 118:22), and using the imagery of Isaiah 8:14, 15 and Daniel 2:44, he describes his fortunes under the imago of a corner-stone - that stone which forms the junction between the two most prominent walls of a building, and which is always laid with peculiar care and attention. In Luke 2:34 of our Gospel Simeon refers to the same well-known prophetic saying. The husbandmen who had just been described as vine-dressers are now described as builders, and the murdered son is reproduced under the image of a corner, stone tossed aside as useless. In the first part of the picture, the earthly humiliation of Messiah is portrayed when the stone is laid in the earth. In the second, the stone falling from the top of the building represents the crushing of all earthly opposition by Messiah in his glory. Woe to the builders, then, who had scornfully rejected him

20:9-19 Christ spake this parable against those who resolved not to own his authority, though the evidence of it was so full. How many resemble the Jews who murdered the prophets and crucified Christ, in their enmity to God, and aversion to his service, desiring to live according to their lusts, without control! Let all who are favoured with God's word, look to it that they make proper use of their advantages. Awful will be the doom, both of those who reject the Son, and of those who profess to reverence Him, yet render not the fruits in due season. Though they could not but own that for such a sin, such a punishment was just, yet they could not bear to hear of it. It is the folly of sinners, that they persevere in sinful ways, though they dread the destruction at the end of those ways.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 Psalm 118:22. See Gill on Matthew 21:42.