Virtues and Merits of the Prophet (pbuh) and his Companions
كتاب المناقب
(14) Chapter: The son of some people's sister is considered as belonging to the same people
باب ابْنُ أُخْتِ الْقَوْمِ وَمَوْلَى الْقَوْمِ مِنْهُمْ
Narrated Anas:
The Prophet (ﷺ) sent for the Ansar (and when they came), he asked, ‘Is there any stranger amongst you?” They said, “No except the son of our sister.” Allah’s Messenger (ﷺ) said, “The son of the sister of some people belongs to them.”