Size of Qur'an readings at evening prayer

فَٱصْبِرْ عَلَىٰ مَا يَقُولُونَ وَسَبِّحْ بِحَمْدِ رَبِّكَ قَبْلَ طُلُوعِ ٱلشَّمْسِ وَقَبْلَ غُرُوبِهَا ۖ وَمِنْ ءَانَآئِ ٱلَّيْلِ فَسَبِّحْ وَأَطْرَافَ ٱلنَّهَارِ لَعَلَّكَ تَرْضَىٰ

Therefore be patient with what they say, and celebrate (constantly) the praises of thy Lord, before the rising of the sun, and before its setting; yea, celebrate them for part of the hours of the night, and at the sides of the day: that thou mayest have (spiritual) joy.

نِّصْفَهُۥٓ أَوِ ٱنقُصْ مِنْهُ قَلِيلًا

Half of it,- or a little less,