Fa-illam yastajeeboo lakum faAAlamoo annama onzila biAAilmi Allahi waan la ilaha illa (surah Hud: 14)

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(11:14) Then if (your deities) do not respond to your call for help then feel assured that this Book was revealed with the knowledge of Allah, and that there is no true god but Him. Will you, then, surrender (to this truth)? *14

Fa il lam yastajeeboo lakum fa`lamooo annamaaa unzilla bi`ilmil laahi wa al laaa ilaaha illaa Huwa fahal antum muslimoon

*14). The argument advanced here serves to establish the divine origin of the Qur'an as well as the oneness of God. The argument, put succinctly, is as follows:
(i) If the unbelievers thought that the Qur'an had been authored by some human being, then it ought to be possible for them to compose something which would be the like of it. Now, unbelievers claim that it is the Prophet (peace be on him) - a human being rather than God - who has produced the Qur'an. In such a case it should be possible for them - for they too are human - to produce such a book. However, despite the repeated challenges for them to produce something like the Qur'an no one, not even all of them combined, has succeeded in achieving it. The conclusion is quite evident: the Book was revealed by God and there is no question that it is the work of any human being.
(ii) The Qur'an quite openly and vehemently denounced the deities which the unbelievers worshipped, and urged them to abandon these as they had no share in God's godhead. The unbelievers were also asked to mobilize all whom they wished, including their deities - provided they had any power - to assist them in establishing the falsity of the Prophet's claim by producing a book equal to the Qur'an. But if at such a crucial stage, their deities fail to come to their aid and do not grant them the power to produce something like the Qur'an, what then does that prove? Quite obviously, it proves that these so-called deities had neither the power nor even a shred of the attributes necessary for godhead. The fact of their becoming deities was purely the work of a few human beings who had invested such weak, mortal creatures with godhead.
Incidentally, this verse also establishes the fact that in terms of chronological sequence the present surah - Hud- was revealed before Surah Yunus. For in the present surah, the unbelievers have been challenged to produce ten surahs like the Qur'anic ones. Subsequently, after the unbelievers failed to do so, they were asked in Surah Yunus to produce just one surah like it. (See Yunus 10: 38, n. 46.)