Musannaf Ibn Abi Shaybah 25275 — Placing water in old waterskins

It is narrated from Abu Uthman al-Nahdi, who said: The Messenger of Allah (peace and blessings be upon him) set out on a military expedition with his Companions. During it, some people in a state of hunger passed by a green tree and began to eat from it. It then seemed as though a wind had come upon them and left them extinguished. At this the Prophet (peace and blessings be upon him) said: "Cool the water in small water-skins, then pour that water over yourselves between the two calls to prayer of the dawn; pour the water down swiftly, and mention the name of Allah over it." So the Companions (may Allah be pleased with them) did this, and (the effect was that) it was as though they had been released from a tether.