'Ubadah bin As-Samit narrated that the Messenger of Allah (s.a.w) said:
"In Paradise, there are a hundred levels, what is between every two levels is like what is between the heavens and the earth. Al-Firdaus is ts highest level, and from it the four rivers of Paradise are made to flow forth. So when you ask Allah, ask Him for Al-Firdaus." (PT)
English reference (PT): Vol. 4, Book 12, Hadith 2531 (PT)
Arabic reference (PT): Book 38, Hadith 2723 (PT)