Sayyiduna Abu Umamah (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) was the most smiling and the most good-natured of people.
Imam al-Tabarani recorded this narration in al-Mu'jam al-Kabir and al-Mu'jam al-Awsat; the chain of this narration contains a narrator, Ali bin Yazid al-Alhani, who is da'if (weak).