He has made it obligatory upon you to recite the Qur'an, to convey it, and to act upon what is in it. This means that the one who has burdened you with the difficulty of this obligation will reward you for it with a reward that cannot be described. And He will certainly return you after death to a place of return, which is a return that is not for others among mankind. The indefinite article used for 'return' indicates this. It is said that it refers to Mecca, and the reasoning is that it refers to his return to it on the day of conquest. The reason for its indefiniteness is that on that day it was a place of return for him, a place of significance, due to the dominance of the Messenger of Allah, blessings and peace be upon him, over it, his overcoming of its people, and the manifestation of the glory of Islam and its people, and the humiliation of polytheism and its party. This surah is Meccan, so it is as if Allah promised him, while he was in Mecca enduring harm and oppression from its people, that he would migrate from it and be returned to it, victorious and triumphant. It is said that it was revealed to him when he reached al-Juhfa in his migration, and he longed for his birthplace and the birthplace of his ancestors and the sanctuary of Ibrahim. Gabriel came down and said to him: 'Do you long for Mecca?' He said: 'Yes,' so it was revealed to him. If you say: How is the saying of Allah, 'Say, my Lord knows' connected to what came before it? I say: When He promised His Messenger the return to the place of return, he said: 'Say to the polytheists: My Lord knows who has brought guidance,' meaning himself and what he deserves of reward in his return, 'and who is in clear error,' meaning them and what they deserve of punishment in their return.