Qabisah bin Dhuw'aib said:
"A grandmother - the mother of a mother, or the mother of a father - came to Abu Bakr and she said: 'a son of my son' - or, 'a son of my daughter died, and I have been informed that there is a right ( from the wealth) for me in the Book.' So Abu Bakr said: 'I do not find that there is a right for you in the Book, and I haven't heard that the Messenger of Allah(S.A.W) judged anything for you. I shall ask the people.' So, Al-Mughirah bin Shu'bah testified that the Messenger of Allah(S.A.W) gave her (case) a sixth. He said: 'And who heard that along with you?' He said: 'Muhammad bin Maslamah." He said: "So he gave her a sixth. Then the other grandmother who was left behind came to 'Umar." Sufyan said: "And Ma'mar said to me in addition, from Az-Zuhri - and I do not remember it to be from A-Zuhri, rather I remember it to be from Ma'mar - that 'Umar said: 'If the two of you are together then it is for both of you, and whichever of you is alone with it (the sixth), then it is for her.'"
English reference: Vol. 4, Book 3, Hadith 2100
Arabic reference: Book 29, Hadith 2246