It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both): "The Prophet (peace and blessings be upon him) mounted Sayyiduna Hasan, Sayyiduna Husayn and Sayyiduna Abdullah bin Ja'far (may Allah be pleased with them) on a single riding animal."
No one narrated these hadiths from Sufyan (may Allah have mercy on him) except Sa'd bin Sa'id (may Allah have mercy on him), and Ishaq bin Ibrahim (may Allah have mercy on him) is alone in narrating them from him.