אֲבָנִ֤ים ׀ שָׁ֥חֲקוּ מַ֗יִם תִּשְׁטֹֽף־סְפִיחֶ֥יהָ עֲפַר־אָ֑רֶץ וְתִקְוַ֖ת אֱנ֣וֹשׁ הֶאֱבַֽדְתָּ׃
The waters wear the stones; The overflowings thereof wash away the dust of the earth; So Thou destroyest the hope of man.
Rashi on Job
Stones which the water eroded by constantly passing over them.
Rashi on Job
it washes away i.e., the flood. its aftergrowth of the stone, to be transformed into dust so that something should grow in it. As the aftergrowths of the harvest grow, so will the aftergrowths of this earth be transformed to stone.
Rashi on Job
but the hope of man is not so, because as soon as he dies, it is lost forever.