רִגְז֗וּ וְֽאַל־תֶּ֫חֱטָ֥אוּ אִמְר֣וּ בִ֭לְבַבְכֶם עַֽל־מִשְׁכַּבְכֶ֗ם וְדֹ֣מּוּ סֶֽלָה׃
Tremble, and sin not; commune with your own heart upon your bed, and be still. Selah
Read kabbalistic (mystical) interpretation of Psalms 4:5: and classical mystical sources.