Musnad Abu Ya'la al-Mawsili 41:13

Abu Bakr ibn Abi Shaybah narrated to us, al-Fadl ibn Dukayn narrated to us, Abd al-Salam ibn Harb narrated to us, from Yazid ibn Abi Ziyad, from Ibn Yakhnas, from Sa'id ibn Zayd ibn 'Amr: That the Prophet, peace and blessings of Allah be upon him, took the hand of al-Hasan ibn 'Ali and said: "O Allah, I love him, so love him."