Translation:

9. 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.

Notes (Tafseer)

5345. Ordinarily secrecy implies deeds of darkness, something which men have to hide; see the next verse. But there are good deeds which may be concerted and done in secret: e.g., charity, or the prevention of mischief, or the defeat of the dark plots of evil. The determining factor is the motive. Is the man doing some wrong or venting his spite, or trying to disobey a lawful command? Or is he doing some good, which out of modesty or self-renunciation he does not want known, or is he in a righteous cause defeating the machinations of Evil, which may involve great sacrifice of himself.?