This Qur’an is also a warning for those who say Allah has begotten a son, this ayah is being addressed to the disbelievers who say this. Why are these people specifically mentioned here separately? It is because majority of the people in the world are involved in attributing a child to Allah ta’ala. At the time of the Prophet sal Allahu alayhi wa sallam, the pagans of Makkah said that the angels were the daughters of Allah. The Jews as well claim that Uzair is the son of Allah, and the Christians say Esa alayhi salaam is the son of Allah.
In the beginning of this surah, Allah mentions three reasons as to why the Qur’an has been sent. Firstly, to warn of a severe punishment. Secondly, to give glad tidings to the righteous believers and thirdly, to specifically warn those who claim a child to Allah ta’ala. From this we learn that there are two types of warning, a general warning–to all of mankind, and a specific warning–to those who ascribe partners to Allah. Those who do shirk have nullified their deeds because they go against the first condition of acceptable deeds, which is sincerity to Allah.
Allah says about them in the next ayah:
No knowledge have they of such a thing, nor had their fathers. Mighty is the word that comes out of their mouths. They utter nothing but a lie. (5)
They do not have any knowledge of what they are saying. When there is no knowledge, only ignorance prevails. The only reason they say Allah has taken a son is because their forefathers said it, so Allah refutes this claim and says neither they nor their forefathers have knowledge. Furthermore, their claim of Allah having a son is a false and fabricated claim, and their daleel (proof) for this claim is that it was said by their forefathers. Just as shirk nullifies their deed; they also do not fulfill the second condition of following the Prophet sal Allahu alayhi wa sallam, but rather they follow their forefathers.
Allah ta’ala says, <<كَبُرَتْ كَلِمَةً>> , kaburat kalimatan, tremendous is this claim of Allah having a son. Allah ta’ala says in surah Maryam 90-91, the heavens almost rupture therefrom and the earth splits open and the mountains collapse in devastation, that they attribute to the Most Merciful a son. It is the biggest and greatest lie to ascribe a partner to Allah ta’ala.
<<إِنْ يَقُولُونَ إِلَّا كَذِبًا>>, they speak nothing but a lie. Kathibaa is the word for lie, and it means something that is contrary to reality. Notice how Allah ta’ala talks about these people: they have NO knowledge, so what they are saying is deemed as a lie, so to speak without knowledge can take one to the level of lying. A lesson for us in this ayah is to not speak without knowledge, to say “I don’t know” and to refrain from exaggeration, because we will be questioned on the Day of Judgment for our actions and statements.