Amir bin Sa'd (may Allah have mercy on him) narrates from his father (may Allah be pleased with him): The Messenger of Allah (peace and blessings be upon him) visited me (when I was ill). I said: O Messenger of Allah (peace and blessings be upon him)! Pray that Allah does not turn me back. He (peace and blessings be upon him) said: "Allah will raise you, and people will benefit from you." I said: I intend to make a bequest, and I have only one daughter; shall I bequeath half? He (peace and blessings be upon him) said: "Half is a lot." I said: A third? He (peace and blessings be upon him) said: "A third is fine, and even a third is a lot." So I bequeathed a third, and he (peace and blessings be upon him) permitted it for me.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الوصايا / 12569