The immediate reference is to the expedition of TABUK, according to the narration of IBN-ABBAS. This was when the prophet returned from TAEF, and prepared Muslims for an expedition to TABUK. Usually the prophet kept the objects and destination of his expeditions secret and strictly confidential, in order to keep the enemy unaware, but this time and in the case of TABUK, he acted openly, due to the importance of the matter, and frankly said to the Muslims that he was going to fight against Roman Emperor! This was to make Muslims know that they proceed on an important strive (JIHAD) and to prepare themselves accordingly for the great content. After all; the distance between Medina and the Roman Border was too long, and too difficult a journey in that awful heat of Arabian summer season. Such matters would show the long expedition difficult and troublesome, and so they were reluctant and slow to co-operate; so much so that their hesitation annoyed the prophet. Therefore the above verses came down to encourage Muslims in a poundeing manner to join the expedition. * * * * * OCCASION OF THE REVELATION (VERSES NO. 38 - 39)