This is the stone
That is, this Jesus of Nazareth, by whose name the lame man was made whole, is that stone spoken of in ( Psalms 118:22 ) by whom is meant the true Messiah, comparable to a stone, for his strength and duration, and usefulness, as a foundation and corner stone, in the spiritual building of the church; and yet notwithstanding is the stone which was set at nought of you builders:
the priests, elders, and Scribes; who were fond of being called builders, but made miserable work of it; despising and rejecting the stone of Israel, and instead of him as a foundation, built themselves, and others, on the traditions of the elders, and their own righteousness: but though Christ was rejected by them, both in person and in doctrine, and was ignominiously treated, and at last put to death, yet he was raised from the dead, and exalted at the right hand of God; and is the stone, which is become the head of the corner;
or the chief corner stone, that adorns, strengthens, knits, and keeps together, the whole building; in which Jews and Gentiles, saints in all ages and places, even all the elect of God, are united together; (See Gill on Matthew 21:42).