Narrated Sa’d:
Allah’s Messenger (#) distributed (Zakat) amongst (a group of) people while | was sitting there but Allah’s Messenger (#) left a man whom | thought the best of the lot. | asked, “O Allah’s Messenger (#)! Why have you left that person? By Allah | regard him as a faithful believer.” The Prophet (#) commented: “Or merely a Muslim.” | remained quiet for a while, but could not help repeating my question because of what | knew about him. And then asked Allah’s Messenger (#), “Why have you left so and so? By Allah! He is a faithful believer.” The Prophet (#) again said, “Or merely a Muslim.” And | could not help repeating my question because of what | knew about him. Then the Prophet (#) said, “O Sa’d! | give to a person while another is dearer to me, for fear that he might be thrown on his face in the Fire by Allah.”

Sahi Al Bukhari 27, Book 2, Hadith 27;