Musannaf Ibn Abi Shayba 27:554

Shababa narrated to us, he said: Shu'bah narrated to us, from 'Adi ibn Thabit, from al-Bara', he said: I saw the Prophet (may Allah bless him and grant him peace) carrying al-Hasan ibn 'Ali on his shoulder, and he said: "O Allah, I love him, so love him." Shu'bah said: So I said to 'Adi, "Hasan?" He said, "Yes."