Musnad Abu Ya'la al-Mawsili 1:118

Al-Qawariri narrated to us, Sufyan ibn 'Uyaynah narrated to us, from al-Zuhri, from Qabisah ibn Dhu'ayb: That the grandmother came to Abu Bakr after the death of the Messenger of Allah, may Allah bless him and grant him peace, and said: "I have been informed that I have a right." Abu Bakr said: "I do not find for you any right in the Book, and I have not heard the Messenger of Allah, may Allah bless him and grant him peace, decree anything for you." Al-Mughirah ibn Shu'bah testified and said: "The Messenger of Allah, may Allah bless him and grant him peace, gave her a sixth." He said: "Who testifies with you?" He said: "Muhammad ibn Maslamah." Al-Zuhri said: "She is the mother of the father of the mother or the father." When 'Umar came, the one who differed from her came. 'Umar said: "Whichever of you is alone in it, it is for her. If you both meet, it is between you."