To what extent are Sunan al-Tirmidhi sound and reliable for reliance upon in Prophetic hadiths, and is it considered among the sound books of Sunnah whose hadiths can be trusted alongside Sahih al-Bukhari and Sahih Muslim, or are the Two Sahihs sufficient? And what are the other reliable sound books of Sunnah?

Sunan al-Tirmidhi, or Jami' al-Tirmidhi, is one of the Sunnah books that the Muslim nation has accepted. Its compiler committed himself to include in it only hadiths that a jurist had acted upon or that a mujtahid had used as evidence. He included in it the sound (sahih), the good (hasan), and the weak (da'if), clarifying the status of each. It can be relied upon for sound hadiths, along with other Sunnah books. However, the two Sahihs (Bukhari and Muslim) are not sufficient because they did not encompass all authenticated hadiths. The authentic Sunnah books whose authors intended to restrict themselves to the sound are: Sahih al-Bukhari, Sahih Muslim, Sahih Ibn Khuzaymah, Sahih Ibn Hibban, and Mustadrak al-Hakim. There are other books that contain many sound hadiths, such as Imam Malik's Muwatta' and Imam Ahmad's Musnad.