100 times
قَالَ صلى الله عليه وسلم مَنْ قَالَ: سُبْحَانَ اللَّهِ وَبِحَمْدِهِ فِي يَوْمٍ مِائَةَ مَرَّةٍ حُطَّتْ خَطَايَاهُ وَلَوْ كَانَتْ مِثْلَ زَبَدِ الْبَحْر)).
Edition transliteration
Whoever says:(Subhanal-lahi wabihamdih.) a hundred times during the day, his sins are wiped away, even if they are like the foam of the sea.
Meaning
Whoever says:(How perfect Allah is and I praise Him.) a hundred times during the day, his sins are wiped away, even if they are like the foam of the sea.
Source and references
Hisn al-Muslim, entry 254.The reference is copied from the edition; separate editorial verification is not complete yet.
Source edition: Fortress of the Muslim. Open source ↗