זוהר שמות — דף ריט ע”ב

Take for yourself — for your pleasure and benefit. The ketoret weaves bonds, illuminates light, and removes impurity from the world. The letters D-H-V-H unite in the secret of the Holy Name, and each bond ascends as will toward Ein Sof. The ketoret must precede prayer to purify the holy before songs and praises. Blessed is Israel that knows how to rectify from below upward until all is bound as one.