From Sahih Muslim (Hadith 6415):
Zaid b. Arqam reported that Allah's Messenger (ﷺ) said:O Allah,, grant forgiveness to the Ansar, the offspring of the Ansar and the offspring of the offspring of the Ansar. This hadith has been narrated on the authority of Shulba with the same chain of transmitters
Reference: Muslim 6415