Parashas Acharei Mos · Passuk 16:23
Chabad.org — English translation + Rashi
Torah Temima points to Yoma 32a.
English: From where do we know that every immersion requires two sanctifications (of hands and feet)? From the wording “and he shall remove… and wash… and wash… and put on.”
Ribui from doubled language — the doubled “and wash” teaches two kiddushin per tevilah.
Each of the five immersions of the Kohen Gadol on Yom Kippur is accompanied by two sanctifications of the hands and feet — one before the immersion and one after.