“Adonoy Sfatai (O God, my lips) open” (Psalms 51:17). This corresponds to the dancing at a wedding. This is because as long as she [the bride] has not been given for union, she is called a naara (maiden)—spelled without the heh (Zohar II, 38b); numerically equivalent to the three hundred and twenty judgments.
But when she is rectified for union, she is called a naaraH, with the heh. The judgments are mitigated by means of the five alephs of Ehyeh that are in Binah, as is brought in the Pri Etz Chaim, Shaar Amidah.
Thus the bride is still in the category of naara, the three hundred and twenty judgments, and must be mitigated and rectified. This is achieved by dancing, because the legs correspond to Netzach and Hod. They are lifted up by the heart, i.e., through the joy of the heart. This is seen empirically, that through the joy of the heart we dance. As is written about Yaakov (Genesis 29:1), “Yaakov lifted up his legs,” and Rashi explains that his heart carried his legs. And the heart is Binah, as is written: Binah is the heart, and with it the heart understands (Tikkuney Zohar, Introduction).
Therefore, one has to intend while dancing to draw the alephs in the heart to the bride by means of the legs. She is the aspect of five times din (judgment), which is numerically equivalent to three hundred twenty and to naara. And through the light of the heart that is drawn to her, she becomes naarah, with a heh, and five times Adonoy.
This is the meaning of, “Adonoy (O God), open my lips.” Through the lips, which are Netzach and Hod, the bride is opened and mitigated in the aspect of union. She becomes the aspect of Adonoy, naarah, fitting for union.
This is what is found in the Midrash (Bereishit Rabbah 70:19): At the wedding of Yaakov and Leah, while [the people] were dancing, they sang, “Hei’a lei’a”—to hint to Yaakov that “this is Leah.” This is because Leah is the “hidden world” (Zohar I, 154a), corresponding to the heart, as in (Psalms 119:11), “In my heart I have hidden away Your word.” From there comes the mitigation of the judgments, when the heh is drawn from the heart. This is the meaning of, “heh Leah,” that one must draw the alephs from Leah in order to mitigate and rectify the bride. They were also saying that the bride’s name is Leah, who through her own aspect is mitigated.