Jesus uses a question to teach the crowd. AT: "You should be able to understand that which is written: 'The stone ... cornerstone.'" (See: [[rc://en/ta/man/translate/figs-rquestion]])
This is the first of three metaphors in a prophecy from the book of Psalms. This one refers to the Messiah as if he were a stone that builders chose not to use, but that God made the most important stone. (See: [[rc://en/ta/man/translate/figs-metaphor]])
"The stone which the builders said was not good enough to use for building." In those days people built the walls of houses and other buildings out of stones.
This second metaphor speaks of people who reject the Messiah as if they fall over a stone and are injured. (See: [[rc://en/ta/man/translate/figs-metaphor]])
# will be broken to pieces
This is a result of falling onto the stone. It can be stated in active form. AT: "will break up into pieces" (See: [[rc://en/ta/man/translate/figs-activepassive]])
# But on whomever it falls
"But whomever that stone falls on." This third metaphor speaks about the Messiah judging those who reject him as if he were a large stone that would crush them. (See: [[rc://en/ta/man/translate/figs-metaphor]])