By giving water, whether cold or heated by fire, with a devoted mind, to a (thirsty) guest, according to the best of his might, one acquires the merit of the act of giving food to a hungry man.
अपो हि प्रयतः शीतास्तापिता ज्वलनेन वा। शक्तितोऽतिथये दत्त्वा क्षुधार्तायाश्नुते फलम्॥