כָּל־פֶּ֥טֶר רֶ֖חֶם לִ֑י וְכָֽל־מִקְנְךָ֙ תִּזָּכָ֔ר פֶּ֖טֶר שׁ֥וֹר וָשֶֽׂה׃
All that openeth the womb is Mine; and of all thy cattle thou shalt sanctify the males, the firstlings of ox and sheep.
Read kabbalistic (mystical) interpretation of Exodus 34:19: and classical mystical sources.