Sayyiduna Qurrah bin Iyas (may Allah be pleased with him) said: I went with my father to the Messenger of Allah (peace and blessings be upon him), and we found him (peace and blessings be upon him) with his buttons undone. He turned me around to his (peace and blessings be upon him) back, and placed (my) hand on the Seal of Prophethood.
Hadith Referenceالمعجم الكبير للطبراني / باب القاف / 16114