It is narrated from Sayyiduna al-Abbas bin Abd al-Muttalib (may Allah be pleased with him); he said: We were sitting with the Messenger of Allah (peace and blessings be upon him) at al-Batha' when a cloud passed by, and the Messenger of Allah (peace and blessings be upon him) asked: "Do you know what this is?" We said: Allah and His Messenger know best. He (peace and blessings be upon him) said: "This is al-sahab (cloud)." We also said: This is a cloud. Then he (peace and blessings be upon him) said: "And it is al-muzn (rain cloud)." We also said: It is al-muzn. Then he (peace and blessings be upon him) said: "And it is al-'anan (cloud spread high in the sky)." Then he (peace and blessings be upon him) remained silent for a while, then asked: "Do you know how much distance there is between the heaven and the earth?" We said: Allah and His Messenger know best. He (peace and blessings be upon him) said: "Between the two is a distance of five hundred years' journey, and from each heaven to the next heaven is also a distance of five hundred years' journey, and the thickness of each heaven is also five hundred years' journey. Above the seventh heaven is a sea, between whose top and bottom is the same distance as between the earth and the heaven. Then above that are eight aw'al (angels in the form of mountain goats), between whose knees and hooves is the same distance as between the earth and the heaven. And Allah Almighty is above even that, and nothing of the deeds of the children of Adam is hidden from Him." This hadith has a sahih (authentic) chain of narration, but the two Shaykhs (Bukhari and Muslim) did not record it.