Sahih Bukhari Volume 6, Book 66, Hadith 4990

قَالَ ابْنُ شِهَابٍ وَأَخْبَرَنِي خَارِجَةُ بْنُ زَيْدِ بْنِ ثَابِتٍ، سَمِعَ زَيْدَ بْنَ ثَابِتٍ، قَالَ فَقَدْتُ آيَةً مِنَ الأَحْزَابِ حِينَ نَسَخْنَا الْمُصْحَفَ قَدْ كُنْتُ أَسْمَعُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقْرَأُ بِهَا فَالْتَمَسْنَاهَا فَوَجَدْنَاهَا مَعَ خُزَيْمَةَ بْنِ ثَابِتٍ الأَنْصَارِيِّ ‏{‏مِنَ الْمُؤْمِنِينَ رِجَالٌ صَدَقُوا مَا عَاهَدُوا اللَّهَ عَلَيْهِ‏}‏ فَأَلْحَقْنَاهَا فِي سُورَتِهَا فِي الْصُّحَفِ‏.

Zaid bin Thabit added, "A Verse from Surat Ahzab was missed by me when we copied the Qur'an and I used to hear Allah's Apostle reciting it. So we searched for it and found it with Khuzaima bin Thabit Al-Ansari. (That Verse was): 'Among the Believers are men who have been true in their covenant with Allah.' (33.23)