Reference for Pesachim 183:17
בית הפרס דתנן ושוין ב"ש וב"ה
may not enter [the Levitical Camp], this one does enter:<span class="x" onmousemove="('comment',' For his purification rites; v. n. 3.');"><sup>22</sup></span> it is preferable that an affirmative precept which involves kareth<span class="x" onmousemove="('comment',' Sc. the Passover-offering.');"><sup>23</sup></span> should come and override an affirmative precept which does not involve kareth.<span class="x" onmousemove="('comment',' Sc. that a tebul yom must not enter the Levitical Camp. That is derived in Naz. ');"><sup>24</sup></span> Now R'Johanan said: By the law of Torah<span class="x" onmousemove="('comment',' The Pentateuch.');"><sup>25</sup></span> there is not even an affirmative precept in connection therewith, for it is said, And Jehoshaphat stood in the congregation of Judah and Jerusalem, in the house of the Lord, before the new court.<span class="x" onmousemove="('comment',' II Chron. XX, 5.');"><sup>26</sup></span> What does 'the new court' mean? That they innovated a law there and ruled: A tebul yom must not enter the Levitical Camp.<span class="x" onmousemove="('comment',' Since this was all innovation, it is only Rabbinical, and as seen supra it was waived for the sake of the Passover-offering. V. Yeb., Sonc. ed. pp. 31ff notes.');"><sup>27</sup></span> 'Beth ha-peras': for we learned: Now Beth Shammai and Beth Hillel both agree