Musannaf Ibn Abi Shayba 3:5040

Ya'la ibn 'Ubayd narrated to us, from 'Uthman ibn Hakim, from his grandmother, al-Rabab, that 'Uthman ibn Hunayf said: "O slave girl, hand me the prayer mat (khumra)." She said: "I am not praying." He said: "Your menstruation is not in your hand."