حَدَّثَنَا عَبْدُ بْنُ حُمَيْدٍ، حَدَّثَنَا عَبْدُ الْعَزِيزِ بْنُ أَبِي رِزْمَةَ، عَنْ إِسْرَائِيلَ، عَنْ سِمَاكٍ، عَنْ عِكْرِمَةَ، عَنِ ابْنِ عَبَّاسٍ، قَالَ مَرَّ رَجُلٌ مِنْ بَنِي سُلَيْمٍ عَلَى نَفَرٍ مِنْ أَصْحَابِ رَسُولِ اللَّهِ صلى الله عليه وسلم وَمَعَهُ غَنَمٌ لَهُ فَسَلَّمَ عَلَيْهِمْ قَالُوا مَا سَلَّمَ عَلَيْكُمْ إِلاَّ لِيَتَعَوَّذَ مِنْكُمْ فَقَامُوا فَقَتَلُوهُ وَأَخَذُوا غَنَمَهُ فَأَتَوْا بِهَا رَسُولَ اللَّهِ صلى الله عليه وسلم ‏.‏ فَأَنْزَلَ اللَّهُ تَعَالَى ‏(‏ يَا أَيُّهَا الَّذِينَ آمَنُوا إِذَا ضَرَبْتُمْ فِي سَبِيلِ اللَّهِ فَتَبَيَّنُوا وَلاَ تَقُولُوا لِمَنْ أَلْقَى إِلَيْكُمُ السَّلاَمَ لَسْتَ مُؤْمِنًا ‏)‏ ‏.‏ قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ ‏.‏ وَفِي الْبَابِ عَنْ أُسَامَةَ بْنِ زَيْدٍ ‏.‏

Narrated Ibn 'Abbas: "A man from Banu Sulaim who had some sheep with him, passed by some of the Companions of the Messenger of Allah (PBUH). He gave Salam to them and they said: 'He did not give Salam except to protect himself.' So they attacked him, killed him, and took his sheep. They went to the Messenger of Allah (PBUH) with them, and Allah, Most High, revealed: O you who believe! When you go in the cause of Allah, verify and say not to anyone who greets you: "You are not a believer (4:94)." Translation Not Available

Book Ref: Jamiya Tirmidhi Book 47 Hadith 3030
Web Ref:  Jamiya Tirmidhi Vol 5 Book 44 Hadith 3030