Musnad Ahmad 941:86

Yahya ibn Sa'id narrated to us, from al-Taymi, from Abu 'Uthman, from Usama ibn Zayd, who said: The Prophet, peace and blessings of Allah be upon him, used to take me and al-Hasan and say: "O Allah, I love them both, so love them both." Yahya said: Al-Taymi said: "I used to narrate it, then I felt hesitant about it, so I said: 'I have been narrating it for such and such a time,' and I found it written down with me."