It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Food at a wedding for one day is Sunnah, food for two days is extra, and food for three days is showing off and seeking reputation."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11283