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
[Machine] The Messenger of Allah ﷺ said: "Whoever enters without invitation, enters as an intruder and leaves as a thief." Al-Bahrani added: "In the beginning, the wedding feast is a right. Whoever is invited and does not respond, then he has disobeyed Allah and His Messenger." Then Al-Baqi mentioned the rest.
قَالَ رَسُولُ اللهِ ﷺ مَنْ دَخَلَ عَلَى غَيْرِ دَعْوَةٍ دَخَلَ مُغِيرًا وَخَرَجَ سَارِقًا وَزَادَ الْبَحْرَانِيُّ فِي أَوَّلِهِ الْوَلِيمَةُ حَقٌّ مَنْ دُعِيَ فَلَمْ يُجِبْ فَقَدْ عَصَى اللهَ وَرَسُولَهُ ثُمَّ ذَكَرَ الْبَاقِيَ
"مَنْ دُعِيَ فَلَمْ يُجبْ فَقَدْ عَصَى الله وَرَسُولَهُ، وَمَنْ دَخَلَ عَلَى غَير دَعْوَةٍ، دَخَلَ سَارِقًا وَخَرَجَ مُغِيرًا ".
"الوَلِيمَةُ حَقٌّ فَمَنْ لَمْ يُجِبْ فقد عَصَى اللهَ وَرسُولَهُ، وَمَنْ دَخَلَ عَلَى غَيرِ دَعْوَة دَخَلَ سَارِقًا، وَخَرَجَ مُغِيرًا".