(O ye who believe) i.e. the Companions of Muhammad (pbuh); (Obey Allah, and the messenger when He calleth you to that which quickeneth you) to that which honours you, makes you triumphant and reforms you, such as when you are called to fighting, etc., (and know) O believers (that Allah cometh in between) protects (the man and his own heart) He protects the believer and his heart, such that He preserves the heart of the believer by making it firm on faith so that it does not reject faith; and he preserves the heart of the disbeliever by making it firm on disbelief so that it does not accept faith, (and that He it is unto Whom) unto Allah in the Hereafter (ye will be gathered) and thus rewarded you for your works.