Leviticus 14:50 Kabbalah

וְשָׁחַ֖ט אֶת־הַצִּפֹּ֣ר הָאֶחָ֑ת אֶל־כְּלִי־חֶ֖רֶשׂ עַל־מַ֥יִם חַיִּֽים׃

And he shall kill one of the birds in an earthen vessel over running water.

Read kabbalistic (mystical) interpretation of Leviticus 14:50: and classical mystical sources.