וּשְׁלֹשִׁ֥ים יוֹם֙ וּשְׁלֹ֣שֶׁת יָמִ֔ים תֵּשֵׁ֖ב בִּדְמֵ֣י טָהֳרָ֑ה בְּכָל־קֹ֣דֶשׁ לֹֽא־תִגָּ֗ע וְאֶל־הַמִּקְדָּשׁ֙ לֹ֣א תָבֹ֔א עַד־מְלֹ֖את יְמֵ֥י טָהֳרָֽהּ׃
And she shall continue in the blood of purification three and thirty days; she shall touch no hallowed thing, nor come into the sanctuary, until the days of her purification be fulfilled.
Read kabbalistic (mystical) interpretation of Leviticus 12:4: and classical mystical sources.