The Splitting Asunder - 82:12
They know what you do.
In the context of verses 10, 11, 12; the angels in charge over us record and protect what we do:
The Splitting Asunder/82:10
Yet there are protectors over you.
The Splitting Asunder/82:11
They are the honorable recorders.
The Splitting Asunder/82:12
They know what you do.
The Letter Qaf/50:16
We created man and We know well what he whispers to himself. We are nearer to him than his jugular vein.
The Letter Qaf/50:17
On his right and on his left sit two receiving angels, recording.
The Letter Qaf/50:18
Not a word comes out of his mouth except with witnesses watching him.
The Night Comer/86:4
Every person has a guardian over him.
The Thunder/13:11
(For each of them) there are those who watch him from in front of him and from behind him. They guard him by Allah´s command. Unless a community changes itself, Allah does not change their condition. And when Allah wills evil for a people, no power can stop it, nor do they have any protector except Him.