Abu al-Tufayl (may Allah be pleased with him) says: Fatimah (may Allah be pleased with her) came to Abu Bakr (may Allah be pleased with him) and said: "O Caliph of the Messenger of Allah (peace and blessings be upon him)! Are you the heir of the Messenger of Allah (peace and blessings be upon him), or his family?" Abu Bakr (may Allah be pleased with him) said: "Rather, his family are his heirs." Fatimah (may Allah be pleased with her) said: "Then what about the khumus (one-fifth)?" Abu Bakr (may Allah be pleased with him) said: I heard the Messenger of Allah (peace and blessings be upon him) say: "When Allah gives His Prophet a provision and then takes him, that provision belongs to the one who is in charge after him." So when I took charge, I decided to return it to the Muslims. Fatimah (may Allah be pleased with her) said: "You and the Messenger of Allah (peace and blessings be upon him) know best," and then she went back.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الفيء والغنيمة / 12746