From *jьz + *uti(“to put on footwear”). Cognate with Lithuanianišaũti(“to take off footwear”), Latinexuō(“to take off, to take out”) (infinitive exuere), among others. See *obuti(“to put on footwear”) for further etymology.
Trubachyov, Oleg, editor (1983), “*izuti (sę)”, in Этимологический словарь славянских языков [Etymological dictionary of Slavic languages] (in Russian), numbers 9 (*jьz – *klenьje), Moscow: Nauka, page 87
Vasmer, Max (1964–1973) “изу́ть”, in Oleg Trubachyov, transl., Этимологический словарь русского языка [Etymological Dictionary of the Russian Language] (in Russian), Moscow: Progress