﴿ نِّصْفَهُۥٓ أَوِ ٱنقُصْ مِنْهُ قَلِيلًا ﴾

“of one-half thereof - or make it a little less than that,”

a half of it nisfahu substitutes for qalīlan with ‘little’ being little by taking into account the whole night or reduce of it of the half a little up to a third