John 4:8

For His disciples, &c. The word for gives the reason why Jesus asked drink of the woman; because His disciples, from whom otherwise He would have sought food and drink, had gone into the city to buy food. For Jesus wished to drink beside the well, and to drink from it, just as poor travellers are wont to do, especially in Syria and Arabia, and other hot countries where there is a scarcity of water. This happened by Christ's tacit providence, that His disciples being all gone away into the city, He might by Himself be able more easily, in talking with this immodest woman, to spare her shame, and disclose her immodesty, and so convert her to faith and modesty.