Rashi on Leviticus 14:11/רש"י על ויקרא י״ד:י״א

1'לפני ה BEFORE THE LORD — i. e. in the gate of Nicanor and not in the court itself (Sifra, Metzora, Section 3 6; Sotah 8a), since he was still short of atonement (as the sin-offering had not yet been brought, and under such circumstances he was not permitted to enter the court).