Mishkat al-Masabih 9 Supplications كتاب الدعوات 70

وَعَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: ” مَنْ قَالَ: سُبْحَانَ اللَّهِ وَبِحَمْدِهِ فِي يَوْمٍ مِائَةَ مَرَّةٍ حُطَّتْ خَطَايَاهُ وَإِنْ كَانَتْ مِثْلَ زَبَدِ الْبَحْرِ ”

He reported God’s messenger as saying that if anyone says a hundred times in a day, “Glory be to God, and I begin with praise to Him”, his sins will be removed from him though they are like the foam of the sea. (Bukhari and Muslim.)