Ibn Abi al-Zinad said that the jurists of Madinah used to say: A woman does not inherit the wala of any of her near relatives; she inherits only the wala of the one whom she herself freed, or of the one who made a contract of manumission with her and so gained his freedom, or the wala of the freedman of the one whom she freed.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الولاء / 21515