Qur'an, Al-Mujadilah, Surah 58:7, 9

Seest thou not that Allah doth know (all) that is in the heavens and on earth? There is not a secret consultation between three, but He makes the fourth among them, nor between five but He makes the sixth, nor between fewer nor more, but He is in their midst, wheresoever they be: In the end will He tell them the truth of their conduct, on the Day of Judgment. For Allah has full knowledge of all things. O ye who believe! When ye hold secret counsel, do it not for iniquity and hostility, and disobedience to the Prophet; but do it for righteousness and self- restraint; and fear Allah, to Whom ye shall be brought back.