Sahih al-Bukhari 27

Sa'd [ibn Abi Waqqas], may Allah be pleased with him, said that once he was sitting with the Messenger of Allah, may Allah bless him and grant him peace, when the Messenger of Allah, may Allah bless him and grant him peace, was distributing things to a group of people. "The Messenger of Allah, may Allah bless him and grant him peace, left out a man whom I admired. I said, 'Messenger of Allah, what about that person? By Allah, I see him to be a believer (mu'min).' The Prophet said, 'Or just a Muslim?' I was silent for a while and then what I knew about him became too much for me and I repeated what I had said. I replied, 'What about that person? By Allah, I see him to be a believer.' He said, 'Or just a Muslim?' [I was silent for a while.] Then what I knew about him became too much for me again and I repeated what I had said and the Messenger of Allah repeated what he had said. Then he said, 'Sa'd, I give to one man [and leave out] another I love more than him out of fear that Allah might throw him on his face into the Fire.' " Yunus, Salih, Ma'mar and Ibn Akhi az-Zuhri related it from az-Zuhri.