It was narrated that ‘Abbas bin "Abdul-Muttalib said:

We were sitting with the Messenger of Allah (ﷺ) in al-Batha". A cloud passed and the Messenger of Allah (ﷺ) said, "Do you know what this is?" They said, Sahab (a cloud). He said, "And muzn (rain cloud)?” We said, And muzn. He said, "And "anan (clouds)?” And we kept quiet. He said: “Do you know how much (distance) there is between heaven and earth?" We said, Allah and His Messenger know best. He said, “Between them there is (the distance of) five hundred years" march, and between each heaven and another there is (the distance of) five hundred years" march, and the thickness of each heaven is (the distance of) five hundred years. Then above the seventh heaven there is a sea, between whose top and bottom is a distance like that between heaven and earth. Then above that there are eight (angels in the form of) mountain goats. The distance between their hooves and their knees is like the distance between heaven and earth. Then above that is the Throne, and the distance between the bottom and the top of the Throne is like the distance between heaven and earth. Then Allah is above that, may He be blessed and exalted, and none of the deeds of the sons of Adam are hidden from Him."

Musnad Ahmad 1770
Arabic/English book : Book 21, Hadith 1770