Musannaf Ibn Abi Shaybah 26640 — Those who permitted dyeing with black

It is narrated from Qays, the freedman of Sayyiduna Khabbab (may Allah be pleased with him); he said: I went in to Sayyiduna al-Hasan and Sayyiduna al-Husayn (may Allah be pleased with them both), and both of them were dyeing with black.