Sunan Abi Dawud, Hadith 3727 ⓘ
‘Abd Allah b. ‘Umar reported the Prophet as sayings: when one of you is invited for a wedding feast, he must attend it.
حَدَّثَنَا الْقَعْنَبِيُّ، عَنْ مَالِكٍ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " إِذَا دُعِيَ أَحَدُكُمْ إِلَى الْوَلِيمَةِ فَلْيَأْتِهَا " .
also referenced under: Hadith 3736 (DarusSalam)