Apparently, the first person to state this explicitly was Zainuddin bin Ali bin Ahmad (better known as Shahid Thani) in his book titled Masalik. Then, Sayed Muhammad Ali Ameli and the author of Madarek as well as the latter generations of scholars until today have followed suit. Thus, it became an indisputable and widely accepted jurisprudential position among all scholars.
SWALI 79: Mimi nilikuwa nikifanya taqliidi ya Imam Khomeiniy (mwenyezi mungu amrehemu) na baada ya kufariki nakabakia kwenye taqliidi yake kwa ruhusa yako mheshimiwa, na nimesikia ya kuwa nyinyi mnasema ya kuwa ahlil kitaab ni twahara, je inawezekana nikakufuateni nyinyi katika mas’ala haya, ukifahamu ya kuwa mimi nina maingiliano na mahisiano sana na watu hawa? JAWABU: Hakunba kizuizi kufanya hivyo, ikiwa haikuthibiti kwako kuwa Imam Khomeiniy ni mjuzi zaidi.