וְשׁ֖וֹר אוֹ־שֶׂ֑ה אֹת֣וֹ וְאֶת־בְּנ֔וֹ לֹ֥א תִשְׁחֲט֖וּ בְּי֥וֹם אֶחָֽד׃
And whether it be cow or ewe, ye shall not kill it and its young both in one day.
Read kabbalistic (mystical) interpretation of Leviticus 22:28: and classical mystical sources.