Musannaf Ibn Abi Shayba 26:552

Ghundar narrated to us, from Uthman ibn Ghiyath, that al-Hasan used to say regarding a man who embraced Islam at the hands of a man: "He [the one who converted him] has his inheritance, unless he has a sister. If there is a sister, then she has the wealth, and she is more entitled to it."