كتاب البيوع
Read the English translation first, with the original Arabic directly underneath.
Narrated Abu Mas`ud:
An Ansari man, called Abu Shu'aib, came and told his butcher slave, "Prepare meals sufficient for five persons, for I want to invite the Prophet (ﷺ) along with four other persons as I saw signs of hunger on his face." Abu Shu'aib invited them and another person came along with them. The Prophet (ﷺ) said (to Abu Shu'aib), This man followed us, so if you allow him, he will join us, and if you want him to return, he will go back." Abu Shu'aib said, "No, I have allowed him (i.e. he, too, is welcomed to the meal).
إِنَّ هَذَا قَدْ تَبِعَنَا، فَإِنْ شِئْتَ أَنْ تَأْذَنَ لَهُ فَأْذَنْ لَهُ، وَإِنْ شِئْتَ أَنْ يَرْجِعَ رَجَعَ