Say (O Muhammad SAW):"If the Most Beneficent (Allah) had a son (or children as you pretend), then I am the first of Allah"s worshippers [who deny and refute this claim of yours (and the first to believe in Allah Alone and testify that He has no children)]." [Tafsir At-Tabari].
Glorified be the Lord of the heavens and the earth, the Lord of the Throne! Exalted be He from all that they ascribe (to Him).
So leave them (alone) to speak nonsense and play until they meet the Day of theirs, which they have been promised.
It is He (Allah) Who is the only Ilah (God to be worshipped) in the heaven and the only Ilah (God to be worshipped) on the earth. And He is the All-Wise, the All-Knower.
And blessed be He to Whom belongs the kingdom of the heavens and the earth, and all that is between them, and with Whom is the knowledge of the Hour, and to Whom you (all) will be returned.
And those whom they invoke instead of Him have no power of intercession; except those who bear witness to the truth (i.e. believed in the Oneness of Allah, and obeyed His Orders), and they know (the facts about the Oneness of Allah).
And if you ask them who created them, they will surely say:"Allah". How then are they turned away (from the worship of Allah, Who created them)?
(Allah has knowledge) of (Prophet Muhammad"s) saying:"O my Lord! Verily, these are a people who believe not!"
So turn away from them (O Muhammad SAW), and say: Salam (peace)! But they will come to know.