Sunan at-Tirmithiy كتاب الصوم باب ما جاء فى إجابة الصائم الدعوة

حَدَّثَنَا أَزْهَرُ بْنُ مَرْوَانَ الْبَصْرِىُّ حَدَّثَنَا مُحَمَّدُ بْنُ سَوَاءٍ حَدَّثَنَا سَعِيدُ بْنُ أَبِى عَرُوبَةَ عَنْ أَيُّوبَ عَنْ مُحَمَّدِ بْنِ سِيرِينَ عَنْ أَبِى هُرَيْرَةَ عَنِ النَّبِىِّ صلى الله عليه وسلم قَال إِذَا دُعِىَ أَحَدُكُمْ إِلَى طَعَامٍ فَلْيُجِبْ فَإِنْ كَانَ صَائِمًا فَلْيُصَلِّ. يَعْنِى الدُّعَاءَ.
The Prophet, peace and blessings of God be upon him, said, "If any of you is invited to a meal, you should accept. If fasting, you should pray(1)." i.e. make a supplication (asking God to bless the hosts).
(1) This could also mean voluntary units of prayer in the house of the hosts. The Prophet, peace and blessings of God be upon him, did both when he was invited to a meal whilst fasting,