זוהר שמות — דף רנא ע”א

All worlds know that the Holy One has mercy on Israel by virtue of the commandment of the teru’ah they sound to awaken heavenly mercy. Happy is the people who know the teru’ah — who know how to stir up divine compassion. In this palace, the prayers of Israel are sustained by the spirit called Zkhout El, and the letters Yod-Heh-Vav are inscribed upon it from above. Seventy-two lights within this palace receive the prayers of Israel and judge them.