Mawsu'ah al-Asmaa al-Husnaa - Muhammad Al-Tuwaijri (≈ 5000 pages)

Encyclopaedia of the Most Beautiful Names of Allah, by Muhammad Al-Tuwaijri

“Encyclopaedia of the Most Beautiful Names of Allah” in the Light of the Qur’an and Sunnah: A valuable book in which the author, may Allah reward him, has explained the most Beautiful Names of Allah mentioned in the Qur’an and Sunnah, and explained in it their great meanings, their effects on the universe, how to supplicate Allah by them, and the method for worshipping Allah according to them.

This Encyclopaedia falls into four big volumes with nearly 1000 pages each.