Rashi. Commentary to Numbers 8:7. Troyes, France, late 11th century, in, e.g., Rashi. The Torah: With Rashi’s Commentary Translated, Annotated, and Elucidated: Bamidbar/Numbers. Translated and annotated by Yisrael Isser Zvi Herczeg, volume 4, page 91. Brooklyn: Mesorah Publications, 1997.