The origin is uncertain. The same meaning for ṣtt is well attested in the Arabic dialects of Dhofar and Oman (Rhodokanakis 32‒33, Reinhardt 178), but in view of its isolated status within Arabic one may legitimately wonder about the possibility of MSA substratum/adstratum influence. Of some interest may be Arb. ṣitt- ‘what is opposite’ (TA 4 585). Any connection with JPA ṣwt ‘to listen, to give heed’ (DJPA 462), Syr. ṣāt ‘audivit’ (LSyr. 625)? (Kogan 2015:570)