Usually when hadith Al-Thaqalain is mentioned, the two that are mentioned is the Qur’an and the Ahlul Bayt (as). However, in a variation of the hadith, Mola Ali (as) is seen as the second after the Book of Allah (Qur’an), and the Prophet (sawa) explains which is more important..
In many authentic books and narrations such as Al-Kafi, the Prophet said “I am leave among you two weighty things, that if you take them you will never go astray, the Book of Allah (Quran) and my progeny my household (Ahlal bayti).”
However we find another hadith where Ali (as) is the exclusive representitive of Ahlulbayt (as) in the two weighty things:
RasoolAllah (saw) said, “I leave behind two weighty things; Book of Allah and Ali ibn Abi Talib (as). Know that Ali ibn Abi Talib (as) is greater than the Book of Allah because he is the interpreter of the Book of Allah for you.”
Sanad: Muhammad ibn Ali ibn Sokkar narrated from Muhammad ibn Qasim, who narrated from Abbad ibn Yaqoub, who narrated from Shareek, who narrated from Rakeen ibn Rabee, who narrated from Qasim ibn Hassaan, who narrated from Zaid ibn Thabit, who said the above hadith
Source: Irshad Al-Quloob, Volume 2, Page 387; Tafseer Al-Burhaan, Volume 1, Page 33, Hadith #32 (See Image)