וְכֹל֙ שֶׁ֣רֶץ הָע֔וֹף אֲשֶׁר־ל֖וֹ אַרְבַּ֣ע רַגְלָ֑יִם שֶׁ֥קֶץ ה֖וּא לָכֶֽם׃
But all winged swarming things, which have four feet, are a detestable thing unto you.
Read kabbalistic (mystical) interpretation of Leviticus 11:23: and classical mystical sources.