It was narrated that 'Abdullah bin Mas'ood (رضي الله عنه) said:

I was hiding beneath the curtain of the Ka'bah when three men came, a Thaqafi and his two Qurashi in-laws. They were very fat but not very smart. They talked among themselves, then one of them said: Do you think Allah hears what we say? The other said: I think that He will hear us if we raise our voices, but He will not hear us if we lower our voices. The other one said. If He hears some of it He will hear all of it. I mentioned that to the Prophet (ﷺ) 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).