וְנֶאֶסְפוּ־שָׁ֣מָּה כָל־הָעֲדָרִ֗ים וְגָלֲל֤וּ אֶת־הָאֶ֙בֶן֙ מֵעַל֙ פִּ֣י הַבְּאֵ֔ר וְהִשְׁק֖וּ אֶת־הַצֹּ֑אן וְהֵשִׁ֧יבוּ אֶת־הָאֶ֛בֶן עַל־פִּ֥י הַבְּאֵ֖ר לִמְקֹמָֽהּ׃
Ivi radunatesi tutte le gregge, veniva rotolata la pietra d’in su la bocca del pozzo, ed abbeverato il bestiame; indi si rimetteva la pietra al suo luogo, sulla bocca del pozzo.
Rashi on Genesis
ונאספו [AND THITHER WERE ALL THE DROVES] GATHERED — they regularly gathered there because the stone was a heavy one
Radak on Genesis
ונאספו שמה...וגללו, the subject of the verse are the various shepherds who have as yet not been mentioned.