مَا كَانَ لِلّٰهِ اَنْ يَّتَّخِذَ مِنْ وَّلَدٍ سُبْحٰنَهٗ ۗاِذَا قَضٰٓى اَمْرًا فَاِنَّمَا يَقُوْلُ لَهٗ كُنْ فَيَكُوْنُ ۗ ( مريم: ٣٥ )
Maa kaana lillaahi ai yattakhiza minw waladin Subhaanah; izaa qadaaa amran fa innamaa yaqoolu lahoo kun fa yakoon (Maryam 19:35)
It is not [befitting] for Allah to take a son; exalted is He! When He decrees an affair, He only says to it, "Be," and it is. (Maryam  : 35)
1 Mufti Taqi Usmani
It is not for Allah to have a son. Pure is He. When He decides a thing, He simply says to it, “Be” and it comes to be.