Doubt as a Natural Human Response

قَالَ رَبِّ أَنَّىٰ يَكُونُ لِى غُلَـٰمٌ وَكَانَتِ ٱمْرَأَتِى عَاقِرًا وَقَدْ بَلَغْتُ مِنَ ٱلْكِبَرِ عِتِيًّا

He said, "My Lord, how will I have a boy when my wife has been barren and I have reached extreme old age?"