Reference for Shevuot 28:9
ולטעמיך תמני הויין דהא איכא טומאה דקודש וטומאה דמקדש תחלה וסוף
<big><b>GEMARA: </b></big>Said R'Papa to Abaye: TWO, SUBDIVIDED INTO FOUR! They are two, subdivided into six! Knowledge of the uncleanness at the beginning and at the end; knowledge of the holy food at the beginning and at the end; knowledge of the Temple at the beginning and at the end! - But [even] according to your argument, they should be eight; for there is the uncleanness in connection with eating holy food, and the uncleanness in connection with entering the Temple, [necessitating knowledge] both at the beginning and at the end!<span class="x" onmousemove="('comment',' The Mishnah uses the expression , states of knowledge (or, awareness) of the uncleanness. Had the Mishnah used the ,unkgv word , states of forgetfulness (or, unawareness) , it would have been justified in stating that there are only four (v. supra p. 66, n. 1) ; states of awareness are, however, eight; for each state of unawareness must be preceded and followed by a state of awareness.');"><sup>15</sup></span> This is no question; the name uncleanness is the same.<span class="x" onmousemove="('comment',' The states of unawareness of the uncleanness both in connection with eating holy food and entering the Temple are reckoned as coming under one category. There are, therefore, only six states of awareness; before and after, in connection with the unawareness of the holy food; before and after, in connection with the unawareness of the Temple; before and after, in connection with the unawareness of the uncleanness');"><sup>16</sup></span>