عَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ: ((مَنْ صَامَ رَمَضَانَ إِيمَانًا وَاحْتِسَابًا، غُفِرَ لَهُ مَا تَقَدَّمَ مِنْ ذَنْبِهِ (زَادَ فِي رِوَايَةٍ: وَمَا تَأَخَّرَ)))
Narrated from Sayyiduna Abu Huraira (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: Whoever fasts during the month of Ramadan with faith and seeking reward, all his past and future sins will be forgiven.