Muhammad bin Abd al-Rahman bin Thawban (may Allah have mercy on him) says that Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) was asked about a person who died owing the fasts of the month of Ramadan and owing the fasts of another month by vow. He said: Sixty poor people should be fed.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 8219