It is narrated from Sayyiduna Ubadah bin al-Samit (may Allah be pleased with him) that among the rulings of the Messenger of Allah (peace and blessings be upon him) was this: for two grandmothers (paternal or maternal), one-sixth (al-sudus) of the inheritance is fixed, to be divided between them equally. This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but they did not record it.