Ebla

ma-[s]a-a-um /mašāyum/ - to spend the night (VE 816)

PS
*mušy(-at)- - evening (CDG 368; Fronzaroli 1965a: 141, 147, 150; Kogan 2011: 196; Kogan 2015: 33)
Cf. PS *ˀamš-ay- ‘yesterday’.