גְּֽבוּל־שַׂ֭מְתָּ בַּל־יַֽעֲבֹר֑וּן בַּל־יְ֝שׁוּב֗וּן לְכַסּ֥וֹת הָאָֽרֶץ׃
Thou didst set a bound which they should not pass over, That they might not return to cover the earth.
Read midrashic interpretation of Psalms 104:9: and classical rabbinic exegesis.