From Sahih Bukhari (Hadith 3528):
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
Reference: Bukhari 3528