Proverbs 30:21 Midrash

תַּ֣חַת שָׁ֭לוֹשׁ רָ֣גְזָה אֶ֑רֶץ וְתַ֥חַת אַ֝רְבַּ֗ע לֹא־תוּכַ֥ל שְׂאֵֽת׃

For three things the earth doth quake, And for four it cannot endure:

Read midrashic interpretation of Proverbs 30:21: and classical rabbinic exegesis.