TT #35 · Parshas Tazria · Aliyah 1 · Passuk 4
English: She shall sit out thirty-three days in the blood of purification; she shall touch no sacred thing and shall not enter the sanctuary until the days of her purification are complete.
Chabad.org — Chumash, English translation + Rashi for Vayikra 12:4
Torah Temimah cites Shevuos 17b.
E-Daf — Shevuos 17b · Shas.org · Steinsaltz Center — vowelized Shevuos 17b
English: “And you shall not enter the sanctuary” — one who enters the Sanctuary through the roofs is exempt, because the Torah prohibited entry by the ordinary manner of entry.
Definition by textual form
The prohibition of entering the Sanctuary applies to an ordinary manner of entry, not entry through the roofs.