Sunan At-Tirmidhi

Narrated Ya'la bin Murrah:that the Messenger of Allah (ﷺ) said: ""Husain is from me, and I am from Husain. Allah loves whoever loves Husain. Husain is a Sibt among the Asbat."" [Asbat, plural of Sibt: A great tribe. Meaning, Al-Husain would have many offspring, such that they would become a great tribe. And this has indeed occurred. See Tuhfat Al-Ahwadhi]