Ibn 'Abbas (Allah be pleased with them) reported:A man came to the Messenger of Allah (ﷺ) and said: Messenger of Allah, my mother has died (in a state) that she had to observe fasts of a month (of Ramadan). Should I complete (them) on her behalf? thereupon he (the Holy Prophet) said: Would you not pay the debt if your mother had died (without paying it)? He said: Yes. He (the Holy Prophet) said: The debt of Allah deserves more that it should he paid.
وَحَدَّثَنِي أَحْمَدُ بْنُ عُمَرَ الْوَكِيعِيُّ، حَدَّثَنَا حُسَيْنُ بْنُ عَلِيٍّ، عَنْ زَائِدَةَ، عَنْ سُلَيْمَانَ، عَنْ مُسْلِمٍ الْبَطِينِ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، عَنِ ابْنِ عَبَّاسٍ، - رضى الله عنهما - قَالَ جَاءَ رَجُلٌ إِلَى النَّبِيِّ صلى الله عليه وسلم فَقَالَ يَا رَسُولَ اللَّهِ إِنَّ أُمِّي مَاتَتْ وَعَلَيْهَا صَوْمُ شَهْرٍ أَفَأَقْضِيهِ عَنْهَا فَقَالَ " لَوْ كَانَ عَلَى أُمِّكَ دَيْنٌ أَكُنْتَ قَاضِيَهُ عَنْهَا " . قَالَ نَعَمْ . قَالَ " فَدَيْنُ اللَّهِ أَحَقُّ أَنْ يُقْضَى " . قَالَ سُلَيْمَانُ فَقَالَ الْحَكَمُ وَسَلَمَةُ بْنُ كُهَيْلٍ جَمِيعًا وَنَحْنُ جُلُوسٌ حِينَ حَدَّثَ مُسْلِمٌ بِهَذَا الْحَدِيثِ فَقَالاَ سَمِعْنَا مُجَاهِدًا يَذْكُرُ هَذَا عَنِ ابْنِ عَبَّاسٍ.
Muslim
The Book of Fasting • Hadith 200