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."