Allah's Messenger (ﷺ) distributed (Zakat) amongst (a group of) people while
I was sitting there but Allah's Messenger (ﷺ) left a man whom I thought the
best of the lot. I asked, "O Allah's Messenger (ﷺ)! Why have you left that
person? By Allah I regard him as a faithful believer." The Prophet (ﷺ)
commented: "Or merely a Muslim." I remained quiet for a while, but
could not help repeating my question because of what I knew about him.
And then asked Allah's Messenger (ﷺ), "Why have you left so and so? By
Allah! He is a faithful believer." The Prophet (ﷺ) again said, "Or merely
a Muslim." And I could not help repeating my question because of what
I knew about him. Then the Prophet (ﷺ) said, "O Sa'd! I 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."
Sahih al-Bukhari Book 2, Hadith 20