The Messenger of Allah ﷺ said, "In Paradise there are one hundred levels, and the distance between each two levels is like the distance between the heavens and the earth. Firdaws is the highest level, from it the four rivers of Paradise gush forth, and above it is the Throne. So when you ask Allah, ask Him for Firdaws."
أن رسول الله ﷺ قال: في الجنة مائة درجة، ما بين كل درجتين كما بين السماء والأرض، والفردوس أعلاها درجة، ومنها تفجر أنهار الجنة الأربعة، ومن فوقها يكون العرش، فإذا سألتم الله، فسلوه الفردوس.
Tirmidhi (2531), Ibn Khuzayma in Tawhid (184), and Hakim (1/80) all narrated it through the route of Hammam, who said, Zayd bin Aslam narrated to us, from Ata bin Yasar, from Ubada bin Samit, and he mentioned it. Hakim said, "Its isnad is sahih." Its citation has already been given shortly before.