رِيَاضُ الصَّالِحِينَ
Riyad as-Salihin 737
The Book About the Etiquette of Eating
Response to an Invitation Extended to a Man Observing Saum (Fasting)
عَنْ أبى هُرَيْرَةَ رضى اللَّه عَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّه عَلَيْهِ وَسَلَّمَ : إِذَا دُعِيَ أَحَدُكُمْ ، فَلْيُجِبْ، فَإِنْ كَانَ صَائِمًا فَلْيُصَلِّ، وَإِنْ كَانَ مُفْطِرًا فَلْيَطْعَمْ .((رَوَاهُ مُسْلِم))
Abu Hurairah (May Allah be pleased with him) reported: The Messenger of Allah (ﷺ) said, "When any of you is invited to a meal, he should accept the invitation. If he is observing Saum (fasting), he should supplicate for the betterment of the host and if he is not fasting, he should eat." [Muslim].
Riyad as-Salihin, 737