﴿ وَبَرًّۢا بِوَٰلِدَتِى وَلَمْ يَجْعَلْنِى جَبَّارًۭا شَقِيًّۭا ﴾

“and [has endowed me with] piety towards my mother; and He has not made me haughty or bereft of grace.”

وَبَرًّ‌ا بِوَالِدَتِي "and (He has made me) good to my mother." - 19:32. Here only the mother is mentioned and not both the parents. Hence it is implied that his birth was a miracle, being without a father. Such a discourse coming from an infant was a miracle by itself to prove his miraculous birth.