Abu Dawud (may Allah have mercy on him) says: I heard (this) from Shu'bah (may Allah have mercy on him) 45 or 46 years ago, that a man came to the Prophet (peace and blessings be upon him) and said: Tell me of a deed that will admit me into Paradise. He (peace and blessings be upon him) said: "Act justly, and give away your surplus wealth." He said: What if I am not able to do that? He (peace and blessings be upon him) said: "Feed people and spread (the greeting of) peace." He said: What if I do not have the strength or the ability for that? He (peace and blessings be upon him) said: "Do you have camels?" He said: Yes. He (peace and blessings be upon him) said: "Take one camel from your camels and a waterskin, and look for a household that only gets to drink water every other day, and give them water to drink. It may be that your camel will not perish and your waterskin will not tear before Paradise becomes due for you."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / 20593