بُلُوغُ الْمَرَامِ
Bulugh al-Maram 1043
Marriage
وَعَنْ اِبْنِ مَسْعُودٍ - رضى الله عنه - قَالَ : قَالَ رَسُولُ اَللَّهِ - صلى الله عليه وسلم -{ طَعَامُ الْوَلِيمَةِ أَوَّلَ يَوْمٍ حَقٌّ , وَطَعَامُ يَوْمِ اَلثَّانِي سُنَّةٌ, وَطَعَامُ يَوْمِ اَلثَّالِثِ سُمْعَةٌ ، وِمَنْ سَمَّعَ سَمَّعَ اللهُ بِهِ } رَوَاهُ اَلتِّرْمِذِيُّ وَاسْتَغْرَبَهُ , وَرِجَالُهُ رِجَالُ اَلصَّحِيحِ [1] .
Narrated Ibn Mas'ud (RA): Allah's Messenger (ﷺ) said: "The food of Walima on the first day is a duty, that on the second day is a Sunnah, while the third is showing off. Whoever (does something) to show-off, Allah will expose him (in the Hereafter)." [Reported by at-Tirmidhi who considered it Gharib (transmitted through a single narrator)]. [It is incorrectly claimed that] its narrators are those who are reported from in the Sahih (collection of al-Bukhari)].
Sunnah.com reference: Book 8, Hadith 92