Musannaf Ibn Abi Shayba 26:100

Waki’ narrated to us, he said: Zakariya narrated to us, from ‘Amir, who said: Masruq was asked about a man who died and had no heir except his maternal uncle and his brother’s daughter. He said: "For the maternal uncle is the share of his sister, and for the brother’s daughter is the share of her father."