מדרש על סנהדרין 43:1

mishneh": This tells me only of mishneh Torah ("the repetition of the Torah," i.e., the book of Devarim). Whence do I derive (that the mitzvah applies also) to the rest of the Torah? From (Ibid. 19) "to heed all the words of this Torah." If so, why is it written "the mishneh of this Torah"? Because it (i.e., the script) is destined to change (viz. Ezra 4:7 and Daniel 5:8).