Likutei Moharan 2:9/ליקוטי מוהר"ן ב׳:ט׳

19. This is the explanation [of the opening verse]: {“God said to Moshe, ‘Speak to the priests, the sons of Aharon, and say to them: Let no [priest] defile himself by [contact with] the dead among his people.’”}

2Speak to the priests — EMoR suggests prayer, as is written (Deuteronomy 26:17), “For God he’EMaRta (you have spoken out) this day.”

3priests — They represent the Torah, the souls, as is written (Malachi 2:7), “For the priest’s lips guard knowledge, and they seek Torah from his mouth.”

4Aharon — He is the aspect of mishpat, as is written (Exodus 28:30), “Aharon shall bear the mishpat of the Israelites [on his heart].” For it is necessary to bring all the prayers to the aspect of Moshe-Mashiach. He will then raise <them, as in, “They brought the Tabernacle to Moshe,” and, “Moshe erected> the Tabernacle.”

5Thus, Rashi explains: “to haZHiR, warn, the grown-ups concerning the little ones. This refers to the tzaddik of the generation, the aspect of Moshe, the great light. He yaZHiR (shines) into and illuminates the prayer, which is the aspect of a small light (see Zohar II, 238b).

6Let no priest defile himself… the dead among his people — This is accomplished by guarding the brit. As is brought in the Zohar (III, 15b): The basic drive of the evil inclination is for sexual promiscuity, this being the fundamental source of defilement.

7And when a person guards the brit, he merits prayer—the aspect of “For my praise, echtom from you.” This is because the sense of smell is mainly dependent upon purity. As our Sages taught: When purity was lost, fragrance was <taken away> (Sotah 49a). As in the incident which the Talmud relates: [Rav Huna found some Hynunus dates and wrapped them in his shawl. Rava, his son, came by] and said to him, “I smell the scent of Hynunus about you.” “My son,” he replied, “you possess purity!”