Genesis 29:8

And they said, We cannot, until all the flocks be gathered together, and till they roll the stone from the well's mouth; then we water the sheep.

They said, We cannot, until. In order to prevent the consequences of too frequent exposure in places where water is scarce, it is not only covered and secured, but it is customary to have all the flocks collected round the well before the covering is removed in presence of the owner, or one of his representatives; and it was for this reason that those who were reposing at the well of Haran with the three flocks were waiting the arrival of Rachel.