John Lightfoot on Luke 13:15

[Doth not each one of you on the sabbath loose his ox?] That disceptation doth attest this, How far a beast going forth. Where it is very much cautioned that the beast be not brought out on the sabbath day carrying any thing upon him that might be a burden not permitted to be borne on that day. They allow that a camel be led out with a halter, a horse with a collar, &c.; that is, when they are led out either to pasture or watering. Nay, the Gloss upon the place adds, "that they may lead out the horse to the water, that he may dip the collar in the water if the water be unclean."

To this may be referred that abstruse and obscure rule concerning the building of mounds about a spring that belongs to a private man, with that art that the beast, being led thither to watering on the sabbath day, shall not go out of the place that is of common right.

It is not only permitted to lead the beast out to watering on the sabbath day, but they might draw water for him, and pour it into troughs, provided only that they do not carry the water, and set it before the beast to drink; but the beast come and drink it of his own accord.