Muhammad bin Sirin said: Sayyiduna al-Hasan bin Ali and Sayyiduna Ibn Abbas (may Allah be pleased with them both) were sitting when a funeral passed by. One of them stood up and the other did not stand. One of them said: "Did the Messenger of Allah (peace and blessings be upon him) not stand?" The other said: "Yes indeed, but then he sat."
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 2730