"Of them, some have fulfilled their obligations (i.e ., have been martyred) and some of them are still waiting, but they have never changed (i.e., they never proved treacherous to their covenant which they concluded with Allah) in the least." (V.33:23)
حَدَّثَنِي مُحَمَّدُ بْنُ بَشَّارٍ، حَدَّثَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ الأَنْصَارِيُّ، قَالَ حَدَّثَنِي أَبِي، عَنْ ثُمَامَةَ، عَنْ أَنَسِ بْنِ مَالِكٍ ـ رضى الله عنه ـ قَالَ نُرَى هَذِهِ الآيَةَ نَزَلَتْ فِي أَنَسِ بْنِ النَّضْرِ {مِنَ الْمُؤْمِنِينَ رِجَالٌ صَدَقُوا مَا عَاهَدُوا اللَّهَ عَلَيْهِ} .
Narrated Anas: We think that the Verse: 'Among the Believers are men who have been true to their covenant with Allah.' was revealed in favor of Anas bin An-Nadir.