وَآيَةٌ لَهُمُ اللَّيْلُ نَسْلَخُ مِنْهُ النَّهَارَ
A sign for them is the night: We strip the day away from it.
The verb naslakhu evokes the sensory action of removing a hide. That action is borrowed to portray daylight's departure and the emergence of darkness. Both the hide-removal scene and the changing light are apprehensible in experience.
The connection, however, is not simply a shared visible outline. It is the ordered disclosure of one state when another is removed. This is a conceptual common feature within a metaphor whose source and target scenes are sensory.