"I can not enumerate (how many times) I heard Messenger of Allah (S) reciting - in the two Rak'ah after Al-Maghrib and the two Rak'ah before Salatul-Fajr with: Say: "O you disbelievers!" and Say: "He is Allah the One."  

سَمِعْتُ مِنْ رَسُولِ اللَّهِ ﷺ يَقْرَأُ فِي الرَّكْعَتَيْنِ بَعْدَ الْمَغْرِبِ وَفِي الرَّكْعَتَيْنِ قَبْلَ صَلاَةِ الْفَجْرِ بِ (قُلْ يَا أَيُّهَا الْكَافِرُونَ ) وَ (قُلْ هُوَ اللَّهُ أَحَدٌ ) قَالَ وَفِي الْبَابِ عَنِ ابْنِ عُمَرَ