Related for Bava Metzia 105:6
וניתי דמאי דלמא אתי לאתויי ודאי
— It means that he has not [yet] redeemed [any other].<span class="x" onmousemove="('comment',' So that he has no money with which it may be retrospectively redeemed. ');"><sup>16</sup></span> Then let him bring the other tithe [produce] which he has and combine them?<span class="x" onmousemove="('comment',' I.e., the tithe which is intermixed and that which he brings, and then redeem both. ');"><sup>17</sup></span> — That [which is tithe] by Biblical law and that which is [so] only by Rabbinic law cannot be combined.<span class="x" onmousemove="('comment',' By Biblical law the tithe is certainly neutralised by a greater quantity than itself. Consequently, when it is thus intermixed, it is tithe only by Rabbinic law, whereas what is brought now is tithe according to Biblical law, and the two cannot be combined for the purpose of joint redemption, with the result that the tithe which he brings will remain unredeemed. But the retrospective combination permitted by Hezekiah is with produce that is already redeemed: hence it does not matter that the first was tithe by Biblical law and the second, sc. the mixed produce, only by Rabbinic law. ');"><sup>18</sup></span>