Where does “زُلَف” come from?

زُلَف (Arabic) comes from Arabic زُلْفَة, from Arabic زَلَفَ — to get close, to advance.

Ancestry of “زُلَف”, step by step

Step	Language	Word	Meaning
1	Arabic	زُلْفَة	dignity, rank, proximity, a portion of the night
2	Arabic	زَلَفَ	to get close, to advance