וְצִוָּה֙ הַכֹּהֵ֔ן וְלָקַ֧ח לַמִּטַּהֵ֛ר שְׁתֵּֽי־צִפֳּרִ֥ים חַיּ֖וֹת טְהֹר֑וֹת וְעֵ֣ץ אֶ֔רֶז וּשְׁנִ֥י תוֹלַ֖עַת וְאֵזֹֽב׃
then shall the priest command to take for him that is to be cleansed two living clean birds, and cedar-wood, and scarlet, and hyssop.
Read kabbalistic (mystical) interpretation of Leviticus 14:4: and classical mystical sources.