While engaging in a hidden wicked deed, there are those who assume that nobody sees them and thus feel relieved. The fact is, however, that Allah sees everything in the heavens and on the Earth. Moment by moment, He witnesses everything a man does. People will give an account of everything they do on the Day of Judgment, when everyone congregates in Allah's presence. The Prophet Muhammad (saas) called attention to this important fact, and reminded his people that, whether one is open or secretive, Allah knows everything. Some of the verses about this issue are as follows:

Say, “Whether you conceal what is in your breasts or make it known, Allah knows it. He knows what is in the heavens and what is on the Earth. Allah has power overall things.” (Surah Al ‘Imran, 29)

Say: “Allah is a sufficient witness between me and you. He is certainly aware of and sees His servants.” (Surat al-Isra’, 96)

If they turn their backs, then say: “I have warned you all alike, though I do not know if the scourge you have been threatened with is near or far. He knows what is said openly and He knows what you hide.” (Surat al-Anbiya’,109-110)

Say: “Allah is a sufficient witness between me and you. He knows everything in the heavens and on the Earth. Those who believe in falsehood and reject Allah shall have much to lose.” (Surat al-’Ankabut, 52)

Say: “Do you presume to teach Allah your religion when Allah knows everything in the heavens and everything on the Earth? Allah has knowledge of all things.” (Surat al-Hujurat, 16)