Jami at-Tirmidhi 781
Jami at-Tirmidhi · Book 8: The Book on Fasting · What Has Been Related About The Fasting Person Accepting The Invitation (To A Meal)
Abu Hurairah narrated that :
حَدَّثَنَا نَصْرُ بْنُ عَلِيٍّ ، حَدَّثَنَا سُفْيَانُ بْنُ عُيَيْنَةَ ، عَنْ أَبِي الزِّنَادِ ، عَنِ الأَعْرَجِ ، عَنْ أَبِي هُرَيْرَةَ ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " إِذَا دُعِيَ أَحَدُكُمْ وَهُوَ صَائِمٌ فَلْيَقُلْ إِنِّي صَائِمٌ " . قَالَ أَبُو عِيسَى وَكِلاَ الْحَدِيثَيْنِ فِي هَذَا الْبَابِ عَنْ أَبِي هُرَيْرَةَ حَسَنٌ صَحِيحٌ .
The Prophet said: "When one of you is invited (to a meal) and he is fasting, then let him said: 'Indeed I am fasting.'"
Grade: Sahih (Darussalam)