Sunan an-Nasa'i, Book 47, Hadith 9 (In-Book) ⓘ
It was narrated from Sa'd that : The Messenger of Allah [SAW] distributed (some spoils of war) and gave to some people but withheld from others. I said: "O Messenger of Allah, you gave to so-and-so and so-and-so, and you withheld from so-and-so, who is a beliver." He said: "Do not say 'a believer,' say 'a Muslim.'" Ibn Shihab (one of the narrators) said: The Bedouins say: "We believe".
أَخْبَرَنَا عَمْرُو بْنُ مَنْصُورٍ، قَالَ حَدَّثَنَا هِشَامُ بْنُ عَبْدِ الْمَلِكِ، قَالَ حَدَّثَنَا سَلاَّمُ بْنُ أَبِي مُطِيعٍ، قَالَ سَمِعْتُ مَعْمَرًا، عَنِ الزُّهْرِيِّ، عَنْ عَامِرِ بْنِ سَعْدٍ، عَنْ سَعْدٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَسَمَ قَسْمًا فَأَعْطَى نَاسًا وَمَنَعَ آخَرِينَ فَقُلْتُ يَا رَسُولَ اللَّهِ أَعْطَيْتَ فُلاَنًا وَمَنَعْتَ فُلاَنًا وَهُوَ مُؤْمِنٌ . قَالَ " لاَ تَقُلْ مُؤْمِنٌ وَقُلْ مُسْلِمٌ " . قَالَ ابْنُ شِهَابٍ { قَالَتِ الأَعْرَابُ آمَنَّا } .
also referenced under: Hadith 4993 (Reference) & Volume 6, Book 47, Hadith 4996 (DarusSalam)