when one of you is invited for a wedding feast, he must attend it.  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ إِذَا دُعِيَ أَحَدُكُمْ إِلَى الْوَلِيمَةِ فَلْيَأْتِهَا  

If he is not fasting, he should eat, and if he is fasting, he should leave it.  

قَالَ رَسُولُ اللَّهِ ﷺ بِمَعْنَاهُ زَادَ فَإِنْ كَانَ مُفْطِرًا فَلْيَطْعَمْ وَإِنْ كَانَ صَائِمًا فَلْيَدْعُ  

if one of you invites his brother, he should accept(the invitation), whether it is a wedding feast or something of that nature.  

قَالَ رَسُولُ اللَّهِ ﷺ إِذَا دَعَا أَحَدُكُمْ أَخَاهُ فَلْيُجِبْ عُرْسًا كَانَ أَوْ نَحْوَهُ  

The tradition mentioned above has also been transmitted by Nafi’ to the same effect through the chain of narrators as mentioned in Ayyub.  

عَنْ نَافِعٍ بِإِسْنَادِ أَيُّوبَ وَمَعْنَاهُ  

when one of you is invited to a meal, he must accept. If he wishes he may eat, but if he wishes(to leave), he may leave.  

قَالَ رَسُولُ اللَّهِ ﷺ مَنْ دُعِيَ فَلْيُجِبْ فَإِنْ شَاءَ طَعِمَ وَإِنْ شَاءَ تَرَكَ  

The Prophet ﷺ said: He who does not accept an invitation which he receives has disobeyed Allah and His Apostle, and he who enters without invitation enters as a thief and goes out as a raider. Abu Dawud said: Aban bin Tariq is unknown.  

قَالَ رَسُولُ اللَّهِ ﷺ مَنْ دُعِيَ فَلَمْ يُجِبْ فَقَدْ عَصَى اللَّهَ وَرَسُولَهُ وَمَنْ دَخَلَ عَلَى غَيْرِ دَعْوَةٍ دَخَلَ سَارِقًا وَخَرَجَ مُغِيرًا  

The worst kind of food is that at a wedding feast to which the rich are invited and from which the poor are left out. If anyone does not attend the feast to which he was invited, he has disobeyed Allah and His Apostle (may peace upon him).  

أَنَّهُ كَانَ يَقُولُ شَرُّ الطَّعَامِ طَعَامُ الْوَلِيمَةِ يُدْعَى لَهَا الأَغْنِيَاءُ وَيُتْرَكُ الْمَسَاكِينُ وَمَنْ لَمْ يَأْتِ الدَّعْوَةَ فَقَدْ عَصَى اللَّهَ وَرَسُولَهُ