In this background...
In this background, Allah calls the men to be His good servants, to worship Him and to join, not the disbelievers and the hypocrites, but the pious ones, those who guard themselves against evil. This context shows that the clause, “so that you may guard (against evil)”, is governed by the verb “worship” - you should worship Allah to join those who guard against evil, who are pious.
It may also be governed by the verb, “created” - Allah created you in order that you may guard yourselves against evil. Qur’an: Who made the earth a bed . . . do not set up equals to Allah while you know: “al-Andad” ( الأنداد ) is plural of an-nidd ( النِّد = alike, equal, peer). The phrase, “while you know”, is unconditional, and grammatically it is circumstantial phrase of ”do not set up”; these two factors lend extra-ordinary force to the prohibition of setting up equals to Allah.
The sentence shows that a man who has even a little knowledge should not ascribe any equal or partner to Allah; he should know that it is Allah Who has created him and those before him and arranged and managed this system in the creation for their sustenance and survival. Qur’an: And if you are in doubt . . . then produce a chapter like it . . . : It is a challenge which human beings and jinn can never meet.
This challenge has been offered to demonstrate the miracle of the Qur'an, to show that it is a Book sent down by Allah, there is no doubt in it; that it has been revealed as an everlasting miracle that will remain alive till the end of the world. This challenge has repeatedly been given in the Qur' an: Say: “If men and jinn should combine together to bring the like of this Qur'an, they could not bring the like of it, even though some of them were aiders of the others” (17:88).
Or, do they say: “He has forged it?” Say: “Then bring ten chapters like it forged and call upon whom you can besides Allah, if you are truthful” (11:13). This context shows that the pronoun “it” in “like it” refers to “that which We have revealed to Our servant”, that is, the Qur'an. It is a challenge to them to bring a like of the Qur'an in its inimitable style and meaning. The word “min mithlihi” ( من مثلهِ = translated here as “like it”) may also be rendered as “from like him”.
In that case it will be a challenge to bring a like of the Qur'an written by someone like the Holy Prophet.