بُلُوغُ الْمَرَامِ
Bulugh al-Maram 679
Fasting
وَعَنْ عَائِشَةَ رَضِيَ اَللَّهُ عَنْهَا; أَنَّ رَسُولَ اَللَّهِ - صلى الله عليه وسلم -قَالَ: { مَنْ مَاتَ وَعَلَيْهِ صِيَامٌ صَامَ عَنْهُ وَلِيُّهُ } مُتَّفَقٌ عَلَيْهِ [1] .
'A’isha (RAA) narrated that The Messenger of Allah (ﷺ) said: "Whoever dies while he still has some fasts to make up (of the days of Ramadan), then his heir (any of them) should fast on his behalf.” Agreed upon.
Arabic/English book reference: Book 5, Hadith 699