Sahih Bukhari

Narrated Ibn Mas`ud:(regarding) the Verse: 'And you have not been screening against yourself lest your ears, and your eyes and your skins should testify against you..' (41.22) While two persons from Quraish and their brother-in-law from Thaqif (or two persons from Thaqif and their brother-in-law from Quraish) were in a house, they said to each other, ""Do you think that Allah hears our talks?"" Some said, ""He hears a portion thereof"" Others said, ""If He can hear a portion of it, He can hear all of it."" Then the following Verse was revealed: 'And you have not been screening against yourself lest your ears, and your eyes and your skins should testify against you