The Prophet of Allah ﷺ would take me and seat me on one of his thighs and seat Hasan bin Ali on the other thigh, then he would embrace us both and say, "O Allah, have mercy on them, for I have mercy on them."My father said, Ali bin al-Madini said, He is al-Suli, from Anazah, tracing back to Rabia, meaning Abu Tamimah al-Suli.
حدثنا عارم بن الفضل حدثنا معتمر عن أبيه قال سمعت أبا تميمة يحدث عن أبي عثمان النهدي يحدثه أبو عثمان
كان نبي الله ﷺ يأخذني فيقعدني على فخذه ويقعد الحسن بن علي على فخذه الأخرى ثم يضمنا ثم يقول اللهم ارحمهما فإني أرحمهما قال أبي قال علي بن المديني هو السلي من عنزة إلى ربيعة يعني أبا تميمة السلي
Its isnad is sahih. Abu Tamimah is al-Hujaymi al-Sulami, whose name is Tarif bin Mujalid, and he is mentioned frequently. He is trustworthy, and his hadith appears in Bukhari and the four (Sunan works). Bukhari related the hadith at 10/434, number 6003, in Fath (Fath al-Bari), in the Book of Manners, chapter on placing the child on the thigh.