And We have made the night as a covering,meaning, its shade and darkness covers the people.This is as Allah says,وَالَّيْلِ إِذَا يَغْشَـهَاBy the night as it conceals it. (91:4)Qatadah commented; وَجَعَلْنَا الَّيْلَ لِبَاساً meaning, a tranquil residence.Concerning Allah's statement,وَجَعَلْنَا النَّهَارَ مَعَاشًا