Musannaf Ibn Abi Shayba 1:1574

Waki’ narrated to us, from Isma’il bin Abi Khalid, from Hakim bin Jabir, who said: My father sent a freedwoman of ours to al-Hasan bin ‘Ali. She saw him perform ablution, and he took a rag after the ablution and wiped himself with it. It was as if she disliked it, and she saw from the wetness [on the rag] as if she was striking it together.