Surah 9 (Taubah), Ayah 119 specifies Ahlul Bayt as the Truthful Ones.
يَا أَيُّهَا الَّذِينَ آمَنُواْ اتَّقُواْ اللّهَ وَكُونُواْ مَعَ الصَّادِقِينَ
O' Men of Faith! Safeguard yourselves against evil [be Muttaqi] and associates yourselves with the Truthful Ones.
Commentary
The Holy Quran commands the faithful to associate with Al‑Saadiqeenالصـادقـيـن (the Truthful Ones), which means: the Holy Prophet and his Ahlul Bayt. The authentic books concur in reporting that this verse refers to Ahlul Bayt. [9]
Polytheism (plural deity or Ghayr‑Allah) is the worst falsehood. Ali had never worshipped (Ghayr‑Allah), he worshipped none but Allah all the way through. And only Ali is known as the كرم الله وجهه Karramallaahu wajhahu, the genuine truthful —and so are the Imams among the purified Ahlul Bayt of the Prophet (pbuh). No one, therefore, except those mentioned in Ahzaab: 33 and Aali Imraan: 61, are meant to be Al‑Saadiqeen (the truthful). Thus this Ayah is explicit (though indirectly), in that Al‑Saadiqeen are Ahlul Bayt themselves. Thus we are enjoined to associate ourselves with their cause.
9: (See Ibn Hajar, Al‑Sawaa'iq Al‑Muhriqa, Chapter 11, Page 90. Also Al‑Razi, Tafseer Kabir, Vol. 16, Page 220 and 221.)
source : /H-21-Math'habs/Quran-Ahlul-6.htm#_Toc67275487
