cast away stones - as out of a garden or vineyard (Isa 5:2).
gather - for building; figuratively, the Gentiles, once castaway stones, were in due time made parts of the spiritual building (Eph 2:19, Eph 2:20), and children of Abraham (Mat 3:9); so the restored Jews hereafter (Psa 102:13, Psa 102:14; Zec 9:16).