﴿ يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ مَا لَكُمْ إِذَا قِيلَ لَكُمُ ٱنفِرُوا۟ فِى سَبِيلِ ٱللَّهِ ٱثَّاقَلْتُمْ إِلَى ٱلْأَرْضِ ۚ أَرَضِيتُم بِٱلْحَيَوٰةِ ٱلدُّنْيَا مِنَ ٱلْءَاخِرَةِ ۚ فَمَا مَتَٰعُ ٱلْحَيَوٰةِ ٱلدُّنْيَا فِى ٱلْءَاخِرَةِ إِلَّا قَلِيلٌ ﴾

“O YOU who have attained to faith! What is amiss with you that, when you are called upon, "Go forth to war in God's cause," you cling heavily to the earth? Would you content yourselves with [the comforts of] this worldly life in preference to [the good of] the life to come? But the enjoyment of life in this world is but a paltry thing when compared with the life to come!”

(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.