﴿ وَيُنذِرَ ٱلَّذِينَ قَالُوا۟ ٱتَّخَذَ ٱللَّهُ وَلَدًۭا ﴾

“Furthermore, [this divine writ is meant] to warn all those who assert, "God has taken unto Himself a son."”

(And to warn) and so that Muhammad (pbuh) warns by means of the Qur'an (those who say: Allah hath chosen a son) i.e. the Jews, Christians and idolaters,