Abu Shuayb had a servant who was a butcher. When he saw the strain that the Messenger of Allah ﷺ was suffering from hunger, he ordered his servant to prepare food enough for five people, then sent word to the Messenger of Allah ﷺ saying, "Come to us as the fifth of five."The Messenger of Allah ﷺ set out, and a man followed him. When they reached the door, the Messenger of Allah ﷺ said, "You sent for me to come as the fifth of five, but this man has followed us. If you permit him, he may enter. Otherwise, he will turn back."Abu Shuayb replied, "I grant him permission, Messenger of Allah," so the man entered.
حدثنا أحمد بن عبد الملك حدثنا زهير عن الأعمش عن أبي سفيان
كان لأبي شعيب غلام لحام فلما رأى ما برسول الله من الجهد أمر غلامه أن يجعل له طعاما يكفي خمسة فأرسل إلى رسول الله ﷺ أن ائتنا خامس خمسة فقام رسول الله ﷺ واتبعه رجل فلما انتهيا إلى بابه قال إنك أرسلت إلي أن آتيك خامس خمسة وإن هذا قد اتبعنا فإن أذنت له دخل وإلا رجع قال فإني قد أذنت له يا رسول الله فدخل
Its chain of transmission is sahih. It is found in Bukhari, 4/312, no. 2081, Fath, in the Book of Sales, chapter on what is said about the meat seller and the butcher, and in Muslim, 3/1608, no. 2036, in the Book of Drinks, chapter on what a guest should do if someone else follows him, and in Tabarani's Al-Kabir, 17/197.