Word by Word Analysis

وَمَا كَانَ لِمُؤْمِنٍ وَلَا مُؤْمِنَةٍ إِذَا قَضَى ٱللَّهُ وَرَسُولُهُۥٓ أَمْرًا أَن يَكُونَ لَهُمُ ٱلْخِيَرَةُ مِنْ أَمْرِهِمْ ۗ وَمَن يَعْصِ ٱللَّهَ وَرَسُولَهُۥ فَقَدْ ضَلَّ ضَلَـٰلًا مُّبِينًا 36

It is not for a believing man or a believing woman, when Allāh and His Messenger have decided a matter, that they should [thereafter] have any choice about their affair. And whoever disobeys Allāh and His Messenger has certainly strayed into clear error.