Narrated Abu Huraira (RA): The Prophet (ﷺ) said, "Whoever believes in Allah and His Apostle, offer prayer perfectly and fasts the month of Ramadan, will rightfully be granted Paradise by Allah, no matter whether he fights in Allah's Cause or remains in the land where he is born." The people said, "O Allah's Messenger (ﷺ)! Shall we acquaint the people with the is good news?" He (ﷺ) said, "Paradise has one-hundred grades which Allah has reserved for the Mujahidin who fight in His Cause, and the distance between each of two grades is like the distance between the Heaven and the Earth. So, when you ask Allah (for something), ask for Al-firdaus which is the best and highest part of Paradise." The sub-narrator added, "I think the Prophet (ﷺ) also said, 'Above it (i.e. Al-Firdaus) is the Throne of Beneficent (i.e. Allah), and from it originate the rivers of Paradise."

Reference: Bukhari: 2790