Regarding supplication for the one who provided the food
حَدَّثَنَا مُحَمَّدُ بْنُ بَشَّارٍ، حَدَّثَنَا أَبُو أَحْمَدَ، حَدَّثَنَا سُفْيَانُ، عَنْ يَزِيدَ أَبِي خَالِدٍ الدَّالاَنِيِّ، عَنْ رَجُلٍ، عَنْ جَابِرِ بْنِ عَبْدِ اللَّهِ، قَالَ صَنَعَ أَبُو الْهَيْثَمِ بْنُ التَّيْهَانِ لِلنَّبِيِّ صلى الله عليه وسلم طَعَامًا فَدَعَا النَّبِيَّ صلى الله عليه وسلم وَأَصْحَابَهُ فَلَمَّا فَرَغُوا قَالَ " أَثِيبُوا أَخَاكُمْ " . قَالُوا يَا رَسُولَ اللَّهِ وَمَا إِثَابَتُهُ قَالَ " إِنَّ الرَّجُلَ إِذَا دُخِلَ بَيْتُهُ فَأُكِلَ طَعَامُهُ وَشُرِبَ شَرَابُهُ فَدَعَوْا لَهُ فَذَلِكَ إِثَابَتُهُ " .
Narrated Jabir ibn Abdullah: AbulHaytham ibn at-Tayhan prepared food for the Messenger of Allah (ﷺ), and he invited the Prophet (ﷺ) and his Companions. When they finished (food), the said: If some people enter the house of a man, his food is eaten and his drink is drunk, and they supplicate (to Allah) for him, this is his reward.