"Guard strictly the (five obligatory) A.s-Salawãt (the prayers), especially the middle SaM! (i.e., the best prayer - 'Asr) .. ." (V.2:238)
حَدَّثَنِي أُمَيَّةُ بْنُ بِسْطَامٍ، حَدَّثَنَا يَزِيدُ بْنُ زُرَيْعٍ، عَنْ حَبِيبٍ، عَنِ ابْنِ أَبِي مُلَيْكَةَ، قَالَ ابْنُ الزُّبَيْرِ قُلْتُ لِعُثْمَانَ بْنِ عَفَّانَ {وَالَّذِينَ يُتَوَفَّوْنَ مِنْكُمْ وَيَذَرُونَ أَزْوَاجًا} قَالَ قَدْ نَسَخَتْهَا الآيَةُ الأُخْرَى فَلِمَ تَكْتُبُهَا أَوْ تَدَعُهَا قَالَ يَا ابْنَ أَخِي، لاَ أُغَيِّرُ شَيْئًا مِنْهُ مِنْ مَكَانِهِ.
Narrated Ibn Az-Zubair: I said to `Uthman bin `Affan (while he was collecting the Qur'an) regarding the Verse:-- "Those of you who die and leave wives ..." (2.240) "This Verse was abrogated by an other Verse. So why should you write it? (Or leave it in the Qur'an)?" `Uthman said. "O son of my brother! I will not shift anything of it from its place."