that the Messenger of Allah said: 'The wedding feast on the first day is an obligation, on the second day is a custom and on the third day is showing off.” (Using translation from Ibn Mājah 1915)   

أَنَّ النَّبِيَّ ﷺ قَالَ الْوَلِيمَةُ أَوَّلَ يَوْمٍ حَقٌّ وَالثَّانِيَ مَعْرُوفٌ وَالْيَوْمَ الثَّالِثَ سُمْعَةٌ وَرِئَاءٌ  

[Machine] The people of Sama'a and Ri'a said, "..."  

وَقَالَ أَهْلُ سُمْعَةٍ وَرِئَاءٍ  

[Machine] And he said, "Go, O people of wealth and fame."  

وَقَالَ اذْهَبُوا أَهْلَ رِئَاءٍ وَسُمْعَةٍ  

[Machine] The Messenger of Allah ﷺ said: The food of the first day is a duty, and the food of the second day is the same. And in the narration of As-Sulami, the food of one day is a duty, the food of two days is a recommended act, and the food of the third day is a virtue and a reward. And whoever feeds others will be fed by Allah and the Sulami did not mention his saying of "reward".  

قَالَ رَسُولُ اللهِ ﷺ طَعَامُ أَوَّلَ يَوْمٍ حَقٌّ وَالثَّانِيَ مِثْلَهُ وَفِي رِوَايَةِ السُّلَمِيِّ طَعَامُ يَوْمٍ حَقٌّ وَطَعَامُ يَوْمَيْنِ سُنَّةٌ وَطَعَامُ الْيَوْمِ الثَّالِثِ سُمْعَةٌ وَرِئَاءٌ وَمَنْ يُسَمِّعْ يُسَمِّعِ اللهُ بِهِ وَلَمْ يَذْكُرِ السُّلَمِيُّ قَوْلَهُ رِئَاءٌ  

[Machine] When Allah's Messenger ﷺ married Umm Salamah, he ordered for a sheep to be slaughtered and then he threw dates and barley upon it. He called people and they ate, and he said that a wedding feast on the first day is a right, on the second day it is customary, and on the third day it is boastful and a matter of reputation. Abu Sa'd Al-Malini, Abu Ahmad ibn 'Adi, Al-Husayn ibn Ismail, Muhammad ibn 'Amr ibn Hayyan, Yahya ibn Sa'id, and Bakr ibn Khunays have all mentioned this narration. However, the reliability of Bakr ibn Khunays is doubted, as people have spoken about him. The narration of Al-Bukhari is also weak. It was narrated from Abu Hurairah in a Marfu' (elevated chain), but it is not reliable. Abu Bakr ibn Ibrahim Al-Farsi mentioned that Ibrahim ibn 'Abdullah narrated from Abu Ahmad ibn Fares, who narrated from Muhammad ibn Ismail Al-Bukhari in a narration of Zuhair ibn 'Uthman, stating that the chain of narrators is not authentic and it is not known to have a reliable companion. Ibn 'Umar and others have mentioned from the Prophet ﷺ that if one of you is invited to a wedding feast, they should accept the invitation and not delay it for more than three days or anything else. This is the most correct view. Ibn Sirin mentioned a story related to this as well.

(Note: The translation is provided to the best of my ability, but some nuances may be lost in translation.  

اللهِ ﷺ لَمَّا تَزَوَّجَ أُمَّ سَلَمَةَ ؓ أَمَرَ بِالنِّطَعِ فَبُسِطَ ثُمَّ أَلْقَى عَلَيْهِ تَمْرًا وَسَوِيقًا فَدَعَا النَّاسَ فَأَكَلُوا وَقَالَ الْوَلِيمَةُ فِي أَوَّلِ يَوْمٍ حَقٌّ وَالثَّانِي مَعْرُوفٌ وَالثَّالِثِ رِئَاءٌ وَسُمْعَةٌ 14513 أَخْبَرَنَا أَبُو سَعْدٍ الْمَالِينِيُّ أنبأ أَبُو أَحْمَدَ بْنُ عَدِيٍّ ثنا الْحُسَيْنُ بْنُ إِسْمَاعِيلَ ثنا مُحَمَّدُ بْنُ عَمْرِو بْنِ حَيَّانَ ثنا يَحْيَى بْنُ سَعِيدٍ عَنْ بَكْرِ بْنِ خُنَيْسٍ فَذَكَرَهُ وَلَيْسَ هَذَا بِقَوِيٍّ بَكْرُ بْنُ خُنَيْسٍ تَكَلَّمُوا فِيهِ وَحَدِيثُ الْبَكَّائِيِّ أَيْضًا غَيْرُ قَوِيٍّ وَرُوِيَ ذَلِكَ عَنْ أَبِي هُرَيْرَةَ مَرْفُوعًا وَلَيْسَ بِشَيْءٍ 14514 وَأَخْبَرَنَا أَبُو بَكْرِ بْنُ إِبْرَاهِيمَ الْفَارِسِيُّ أَنْبَأَ إِبْرَاهِيمُ بْنُ عَبْدِ اللهِ ثنا أَبُو أَحْمَدَ بْنُ فَارِسٍ عَنْ مُحَمَّدِ بْنِ إِسْمَاعِيلَ الْبُخَارِيِّ فِي حَدِيثِ زُهَيْرِ بْنِ عُثْمَانَ قَالَ لَمْ يَصِحَّ إِسْنَادُهُ وَلَا يُعْرَفُ لَهُ صُحْبَةٌ وَقَالَ ابْنُ عُمَرَ وَغَيْرُهُ عَنِ النَّبِيِّ ﷺ إِذَا دُعِيَ أَحَدُكُمْ إِلَى الْوَلِيمَةِ فَلْيُجِبْ وَلَمْ يَخُصَّ ثَلَاثَةَ أَيَّامٍ وَلَا غَيْرَهَا وَهَذَا أَصَحُّ وَذَكَرَ حِكَايَةَ ابْنِ سِيرِينَ  

[Machine] From Ayoub, eight days had passed, and the first was the most accurate.  

عَنْ أَيُّوبَ ثَمَانِيَ أَيَّامٍ وَالْأَوَّلُ أَصَحُّ  

[Machine] My father got married and invited people for eight days. He invited Ubayy ibn Ka'b who came that day while he was fasting and prayed. He said, "He invited with blessings," then he left and Allah knows best.  

تَزَوَّجَ أَبِي فَدَعَا النَّاسَ ثَمَانِيَةَ أَيَّامٍ فَدَعَا أُبَيَّ بْنَ كَعْبٍ فِيمَنْ دَعَا فَجَاءَ يَوْمَئِذٍ وَهُوَ صَائِمٌ وَصَلَّى يَقُولُ دَعَا بِالْبَرَكَةِ ثُمَّ خَرَجَ وَاللهُ أَعْلَمُ