Sahih Muslim Book 23, Hadith Number 5054.

Chapter : What should the guest do if an uninvited person accompanies him and the merit of inviting that person to feast.

Anas reported that Allah’s Messenger (may peace be upon him) had a neighbour who was Persian (by descent), and he was expert in the preparation of soup. He prepared (soup) for Allah’s Messenger (may peace be upon him) and then came to him to invite him (to that feast). He (Allah’s Messenger) said: Here is ‘Aisha also (and you should also invite her to the food). He said: No. Thereupon Allah’s Messenger (may peace be upon him) also said: No (then I cannot join the feast). He returned inviting him, and Allah’s Messenger (may peace be upon him) said: She is also there (i.e. ‘Aisha should also be invited). He said: No. Thereupon Allah’s Messenger (may peace be upon him) also said: No (and declined his offer). He returned again to invite him and Allah’s Messenger (may peace be upon him) again said: She is also there. He (the host) said: “Yes” for the third time. Then he accepted his invitation, and both of them set out until they came to his house.