مسند امام احمد بن حنبل · Hadith 4047

It was narrated that 'Abdullah (RA) said: I was hiding behind the curtain of the Ka'bah, and three people came who were very fat but not very smart, a Qurashi and his two Thaqafi in- laws or a Thaqafi and his two Qurashi in-laws. They said something I did not understand, then one of them said: Do you think Allah hears what we say? The other said: I think if we raise our voices, He will hear us but if we do not raise our voices He will not hear us. The other one said: If He hears some of it He will hear all of it. I mentioned that to the Prophet (PBUH) and Allah, may He be glorified and exalted, revealed the words: "And you have not been hiding yourselves (in the world), lest your ears and your eyes and your skins should testify against you; but you thought that Allah knew not much of what you were doing. And that thought of yours which you thought about your Lord, has brought you to destruction; and you have become (this Day) of those utterly lost [Fussilat 40:22-23].