On the authority of Abu Dharr (may Allah be pleased with him) who said: The messenger of Allah (peace and blessings of Allah be upon him), said: "I see that which you can not see. The heaven overflow (on account of heavy load of the Angels prostrating) and is justified in doing so. There is not a space equal to four fingers in it that is not occupied by an angel who is prostrating before Allah. By Allah, if you could know what I know, you would laugh little and weep much; you would not enjoy your wives in bed, and would rush into streets and jungles in search of Allah's refuge."

(Tirmidhi)