استاك

اِسْتَاكَ • (istāka) VIII (non-past يَسْتَاكُ (yastāku), verbal noun اِسْتِيَاك (istiyāk))

1. (intransitive) to brush one's teeth with a سِوَاك (siwāk, “miswak”)
   • 850–861, علي بن سهل ربن الطبري , edited by Oliver Kahl, ʿAlī ibn Sahl Rabban aṭ-Ṭabarī’s Health Regimen or “Book of the Pearl” كتاب اللؤلؤة (Islamic Philosophy, Theology and Science. Texts and Studies; 115), Leiden: Brill, published 2020, →ISBN, § 80–81, page 102:

     إن من أراد الصحة فينبغي أن يقوم من نومه في السُبْع الأخير من الليل وليسبغ وُضُوءَه ويلبس أنظف ثيابه ويبدأ بحمد الله والتضرع إليه في حاجاته. ويستاك من أشجار مُرّة أو حِرِّيفة.

     He who desires to stay healthy should rise from sleep in the last seventh of the night, expand into a proper ablution, put on his tidiest garment, and begin by praising God and imploring him to provide help when needs befall. He cleans his teeth with a twig from bitter or pungent trees.