(O ye who believe!) the address is to the Companions of Muhammad (pbuh) (What aileth you that when it is said unto you: Go forth) with your Prophet (in the way of Allah) in obedience of Allah at the Battle of Tabuk, (ye are bowed down to the ground with heaviness) you wish to remain bowed down to the ground. (Take ye pleasure in the life of the world) i.e. in that which is in the life of this world (rather than in the Hereafter? The comfort of the life of the world is but little in the Hereafter) and will not last.