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)].