Al-Kāfi

Hadith 340
fastingramadan
2ـ عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ مُحَمَّدِ بْنِ عِيسَى بْنِ عُبَيْدٍ عَنْ يُونُسَ عَنْ عُمَرَ بْنِ أَبَانٍ عَنِ الْمُفَضَّلِ بْنِ عُمَرَ قَالَ سَمِعْتُ أَبَا عَبْدِ الله (عَلَيْهِ السَّلاَم) يَقُولُ صَوْمُ شَعْبَانَ وَشَهْرِ رَمَضَانَ مُتَتَابِعَيْنِ تَوْبَةٌ مِنَ الله.
2. Ali ibn Ibrahim has narrated from Muhammad ibn ‘Isa ibn ‘Ubayd from Yunus from ‘Umar ibn Aban from al-Mufaddal ibn ‘Umar who has said the following: “I heard abu ‘Abd Allah (a.s.), say, ‘Fasting during the month of Sha‘ban and the month of Ramadan in a continuous manner is returning to Allah.’”
Source: Shaykh Muḥammad b. Yaʿqūb al-Kulaynī