hadith
1204
۞
The Prophet (SAWA) said, ‘He who fasts a single day of his own accord, wishing to procure the reward of Allah, [Allah makes] his forgiveness mandatory.
رسولُ اللهِ (صَلَّيَ اللهُ عَلَيهِ وَ آلِهِ): مَن صامَ يَوماً تَطَوُّعاً ابتِغاءَ ثَوابِ اللّهِ وَجَبَت لَهُ المَغفِرَةُ .