וַיֹּאמְרוּ֮ לֹ֣א נוּכַל֒ עַ֣ד אֲשֶׁ֤ר יֵאָֽסְפוּ֙ כָּל־הָ֣עֲדָרִ֔ים וְגָֽלֲלוּ֙ אֶת־הָאֶ֔בֶן מֵעַ֖ל פִּ֣י הַבְּאֵ֑ר וְהִשְׁקִ֖ינוּ הַצֹּֽאן׃
그들이 가로되 우리가 그리하지 못하겠노라 떼가 다 모이고 목자들이 우물 아구에서 돌을 옮겨야 우리가 양에게 물을 먹이느리라
Rashi on Genesis
לא נוכל WE CANNOT — give them water because the stone is a heavy one.
Siftei Chakhamim
To give them drink because the stone is large. Rashi is explaining that they cannot roll it due to its weight, as Rashi said on v. 3, and not because they had so agreed among themselves.
Rashi on Genesis
וגללו AND THEY ROLL AWAY — This word is rendered in the Targum by ויגנדרון “and they will roll away” (whilst in Genesis 5:3 it is rendered by an Aramaic participle) because the verb has here a future meaning.