It is narrated from Hazrat Ubadah bin Samit (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: Paradise has one hundred levels; between each two levels is a distance of one hundred years. The highest rank is the level of Jannat al-Firdous. From it flow the four rivers, and above it is the Throne of Allah. Therefore, when you ask Allah, ask for Jannat al-Firdous.
Hadith Referenceمسند احمد / مسند الأنصار رضي الله عنهم / 22695
Hadith Gradingحکم دارالسلام:حديث صحيح، واختلف فى هذا الإسناد على عطاء بن يسار