Mishkat al-Masabih
Fasting — Hadith #1985
وَعَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ:
" إِذَا دُعِيَ أَحَدُكُمْ إِلَى طَعَامٍ وَهُوَ صَائِمٌ فَلْيَقُلْ: إِنِّي صَائِمٌ ". وَفِي رِوَايَةٍ قَالَ: «إِذَا دُعِيَ أَحَدُكُمْ فَلْيُجِبْ فَإِنْ كَانَ صَائِمًا فَلْيُصَلِّ وَإِن كَانَ مُفطرا فيطعم» . رَوَاهُ مُسلم
Abu Huraira reported God’s messenger as saying, “When one of you is invited to a meal at a time when he is fasting he should say he is fasting.” In a version he said, “When one of you receives an invitation he should accept it. If he is fasting he should pray, but if not, he should eat.”
Muslim transmitted it.