So and so is a martyr, till they happened to pass by a man and said: So and so is a martyr. Upon this the Messenger of Allah remarked: Nay, not so verily I have seen him in the Fire for the garment or cloak that he had stolen from the booty, Then the Messenger of Allah ﷺ said: Umar son of Khattab, go and announce to the people that none but the believers shall enter Paradise. He ('Umar b. Khattab) narrated: I went out and proclaimed: Verily none but the believers would enter Paradise.
لَمَّا كَانَ يَوْمُ خَيْبَرَ أَقْبَلَ نَفَرٌ مِنْ صَحَابَةِ النَّبِيِّ ﷺ فَقَالُوا فُلاَنٌ شَهِيدٌ فُلاَنٌ شَهِيدٌ حَتَّى مَرُّوا عَلَى رَجُلٍ فَقَالُوا فُلاَنٌ شَهِيدٌ فَقَالَ رَسُولُ اللَّهِ ﷺ كَلاَّ إِنِّي رَأَيْتُهُ فِي النَّارِ فِي بُرْدَةٍ غَلَّهَا أَوْ عَبَاءَةٍ ثُمَّ قَالَ رَسُولُ اللَّهِ ﷺ يَا ابْنَ الْخَطَّابِ اذْهَبْ فَنَادِ فِي النَّاسِ إِنَّهُ لاَ يَدْخُلُ الْجَنَّةَ إِلاَّ الْمُؤْمِنُونَ قَالَ فَخَرَجْتُ فَنَادَيْتُ أَلاَ إِنَّهُ لاَ يَدْخُلُ الْجَنَّةَ إِلاَّ الْمُؤْمِنُونَ