A man came to the Messenger of Allah ﷺ and said, "I draw water into my trough until I have filled it for my family, then a camel belonging to someone else comes to me, so I give it to drink. Is there any reward for me in that?"The Messenger of Allah ﷺ replied, "In every living creature with a thirsty liver there is a reward."
حدثنا هارون بن معروف حدثنا عبد الله بن وهب أخبرني أسامة أن
أن رجلا جاء إلى رسول الله ﷺ فقال إني أنزع في حوضي حتى إذا ملأته لأهلي ورد علي البعير لغيري فسقيته فهل لي في ذلك من أجر فقال رسول الله ﷺ في كل ذات كبد حرى أجر
Its isnad is sahih. Usamah is Ibn Zayd Laythi. Haythami mentioned the hadith in Majma al-Zawaid 3/131, and said, Ahmad related it, and its narrators are trustworthy.The word is hara, pronounced with a fatha on the plain ha, a doubled ra, and a short alif, though writing it with a ya is preferable, and that is how it is written in M and in Majma al-Zawaid. In L, Kh, and H it is written Hiraa, with the long alif and the hamza, which is an error.Ibn Athir said, hara follows the pattern of fala, formed from harr (heat), being the feminine of harran, both forms used for emphasis. He means that the liver, because of its intense heat, has become thirsty and dried up from thirst. The meaning is that giving water to any creature with a parched liver brings a reward.It has also been said that by "the parched liver" is meant the life of its owner, for the liver is only parched when there is life in it. That is, it refers to giving water to any living creature possessing a soul among the animals. This is supported by what is mentioned in another hadith, "In every warm liver there is a reward."