the Prophet said: "Whoever died while he had a month to fast, then a needy person should be fed on his behalf in place of every day."  

عَنِ النَّبِيِّ ﷺ قَالَ مَنْ مَاتَ وَعَلَيْهِ صِيَامُ شَهْرٍ فَلْيُطْعِمْ عَنْهُ مَكَانَ كُلِّ يَوْمٍ مِسْكِينًا