Musnad Ahmad 26:523

Hushaym narrated to us, from Ibn Abi Layla, from Abu Qays, from Hudhayl ibn Shurahbil, that al-Ash‘ari was approached regarding a daughter, a son’s daughter, and a sister (full sister, sharing both father and mother). He said: So he assigned half to the daughter, and the remainder to the sister, and he did not assign anything to the son’s daughter. He said: So they came to Ibn Mas‘ud and informed him. He said: He said, "I would have gone astray then, and I would not be among the guided, if I were to take his statement and abandon the statement of the Messenger of Allah, peace and blessings of Allah be upon him." He said: Then Ibn Mas‘ud said: "For the daughter is half, for the son’s daughter is the sixth, and what remains is for the sister."