How many Hadiths have scholars agreed upon their authenticity, and in which books are they found? What are the the types of Hadith that are not acted upon, and are there books that contain them?

It is not possible to determine the exact number of hadiths that scholars have agreed upon as authentic, as they are dispersed throughout the books of Sunnah, though most of them are found in Sahih al-Bukhari and Sahih Muslim, due to the consensus of the Ummah on their acceptance. Scholars have established criteria for an authentic hadith.

As for the hadiths that are not acted upon, they are the abrogated, the fabricated (mawdu'), and those that are extremely weak. However, a weak hadith may be acted upon in matters of virtuous deeds (fada'il al-a'mal) under certain conditions: that it falls under an established principle, that its authenticity is not believed in, and that its weakness is not severe.

Among the books that collected weak and fabricated hadiths are: "Al-Mawdu'at" by Ibn al-Jawzi, "Tanzeeh al-Shari'ah al-Marfu'ah" by Ibn Iraq, "Al-La'ali al-Masnu'ah" by al-Suyuti, "Al-Fawa'id al-Majmu'ah" by al-Shawkani, and "Silsilah al-Ahadith al-Da'ifah wa al-Mawdu'ah" by al-Albani.