Abdullah bin Abi Zuhayr, the freed slave of Sayyiduna Hasan bin Ali (may Allah be pleased with him), said: I saw Sayyiduna Hasan bin Ali (may Allah be pleased with him) applying wasmah (a kind of dye). Al-Hadrami said: Ubadah said it like this, "the freed slave of Hasan", whereas he is the freed slave of Husayn.
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 2518