("It is not for Allah to take any son; exalted is He!") He declares Himself above what they say. ("When He decrees a matter, He only says to it, 'Be,' and it is.") [Meaning: Jesus] it was in His knowledge that he would be without a father.
Muhammad said: His saying ("to take any son"), the meaning is: to take a son, and "min" (any) is emphatic.