(16) باب الأَمْرِ بِإِجَابَةِ الدَّاعِي إِلَى دَعْوَةٍ
Abu Haraira (Allah be pleased with him) reported Allah's Messenger (ﷺ) as saying:
If any one of you is invited, he should accept (the invitation). In case he is fasting, he should pray (in order to bless the inmates of the house), and if he is not fasting he should eat.
Reference: Sahih Muslim 1431
In-book reference: Book 16, Hadith 123
USC-MSA web (English) reference(deprecated numbering scheme): Book 8, Hadith 3348