Zaid bin Arqam, narrated that the messenger of Allah . said: “Indeed, I am leaving among you, that which if you hold fast to them, you shall not be misguided after me. One of then is greater than the other: (First is) The book of Allah is a rope extended from the sky to the earth, and (the second is) my family, the people of my house (ahlul bait), and they shall not split until they meet me at the hawdh, so look at how you deal with them after me.” (Sahih).

Volume 6, Chapter 31, Hadith No. 3786: