A parenthetic remark. The Levites had charge of the stores of spicery, but only the priests might lawfully prepare the holy ointment and oil wherewith the sacred tent, the ark, the table, &c, were anointed (Exodus 30:23-29).
Related Commentaries of 1 Chronicles 9:30
1 Chronicles 9:30
30 And some of the sons of the priests made the ointment of the spices.