ON THE SUBJECT OF 103 THE INVITED AND UNINVITED GUEST; INVITE THE UNEXPECTED FOR FOOD H 746 "A man prepared some food for the Prophet, praise and peace be upon him, and invited him together with four other people, however another person who had not been invited accompanied them. When they arrived at the door, the Prophet, praise and peace be upon him, said to the host: 'This person has accompanied us will you permit him to join us, if not he will return.' The host replied, 'O Messenger of Allah, praise and peace be upon him, indeed he is invited.'" R 746 Bukhari and Muslim with a chain up to Abu Mas'ud Badri who related that the Prophet, praise and peace be upon him, said this.
باب مَا يقوله من دُعي إِلَى طعام فتبعه غيره 738- عن أَبي مسعود البَدْريِّ رضي الله عنه ، قَالَ : دعا رَجُلٌ النَّبِيَّ صلى الله عليه وآله وسلم لِطَعَامٍ صَنعَهُ لَهُ خَامِسَ خَمْسَةٍ ، فَتَبِعَهُمْ رَجُلٌ ، فَلَمَّا بَلَغَ البَابَ ، قَالَ النَّبيّ صلى الله عليه وآله وسلم : "إنَّ هَذَا تَبِعَنَا ، فَإنْ شِئْتَ أنْ تَأْذَنَ لَهُ ، وَإنْ شِئْتَ رَجَعَ" قَالَ : بل آذَنُ لَهُ يَا رَسُولَ الله . متفقٌ عَلَيْهِ .