Sayyiduna Suraqah bin Malik bin Ju'shum (may Allah be pleased with him) said that he came to the beloved Prophet (peace and blessings be upon him) during his illness and said: "Tell me, if a stray animal comes to the trough of my camels, will I get a reward for giving it water?" He (peace and blessings be upon him) said: "Yes! There is a reward in (every) being with a living heart."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7807