Musannaf Ibn Abi Shayba 38:6

Jarir narrated to us, from Ata’ ibn al-Sa’ib, from al-Sha’bi, who said: Ali distributed inheritances before the day of the Camel according to the obligatory shares of the Muslims: for the wife her eighth, and for the daughter her portion, and for the son his obligatory share, and for the mother her allotted share.