Mustadrak al-Hakim — Hadith 8157

It is narrated from Huzayl bin Shurahbil that he said: I came to Sayyiduna Abu Musa and Salman bin Rabi'ah (may Allah be pleased with them both) with a question of inheritance concerning a daughter, a son's daughter and a full sister (from the same father and mother). They both said: The daughter gets half and the sister gets half. And they said: Go to Ibn Mas'ud; he will agree with us. So I went to Ibn Mas'ud (may Allah be pleased with him) and told him what the two of them had said. Ibn Mas'ud (may Allah be pleased with him) said: "Then I would have gone astray and would not be among the rightly guided. Rather, I will judge according to what the Messenger of Allah (peace and blessings be upon him) judged: the daughter gets half (1/2), the son's daughter gets one sixth (1/6) (so that two thirds are completed), and whatever remains is for the sister."
This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim).