It is narrated from Sayyiduna Ibn Mas'ud (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) would often recite «سُبْحَنَكَ رَبَّنَا وَبِحَمْدِكَ اَللّٰهُمَّ اغْفِرْلِيْ» , and when Surah Nasr was revealed to the Prophet (peace and blessings be upon him), he began to say: «سُبْحَانَكَ رَبَّنَا وَبِحَمْدِكَ اللّٰهُمَّ اغْفِرْ لِي إِنَّكَ أَنْتَ التَّوَّابُ الرَّحِيمُ» "O Allah! Forgive me, for You are indeed the Acceptor of repentance, the Most Merciful."