Musnad Ahmad 26:671

Waki’ narrated to us, Sufyan narrated to us, from al-A’mash, from ‘Umarah ibn ‘Umayr al-Taymi, from Wahb ibn Rabi’ah, from ‘Abdullah, who said: I was hidden behind the coverings of the Ka’bah when two Thaqafi men entered, and their brother-in-law was a Qurashi, or two Qurashi men and their brother-in-law was a Thaqafi. They had much fat in their bellies and little understanding in their hearts. They spoke a conversation among themselves, and one of them said to his companion: "Do you think Allah, the Mighty and Majestic, hears what we are saying?" The other said: "I think He hears if we raise our voices, but He does not hear if we whisper." The other said: "If He hears some of it, He surely hears all of it." I came to the Prophet, peace and blessings of Allah be upon him, and mentioned that to him. Then Allah, the Mighty and Majestic, revealed: "And you were not covering yourselves, lest your hearing, your sight, and your skins should testify against you..." [Fussilat: 22].