How many levels does Paradise have, what is the highest among them, and what is the way to reach it?

Paradise has a hundred levels, the highest of which is Al-Firdaws. The distance between any two levels is like the distance between the sky and the earth. From Al-Firdaws gush forth the four rivers of Paradise, and above it is the Throne. The way to reach it is by obeying Allah and His Messenger, by fulfilling commands and avoiding prohibitions, by hoping for reward and fearing punishment, and by frequent supplication.