Musannaf Ibn Abi Shayba 26:66

Ibn al-Mubarak narrated to us, from Ma’mar, from Simak ibn al-Fadl, who said: I heard Wahb narrating from al-Hakam ibn Mas’ud, who said: I witnessed ‘Umar include the siblings from the father and mother with the siblings from the mother in the one-third [share of the inheritance]. A man said to him: "You judged differently regarding this last year." He said: "And how did you judge?" He replied: "You assigned it to the mother and did not assign anything to the siblings from the father and mother." He said: "That was based on what we judged then, and this is based on what we judge now."