The sons of the priests made the ointment - Only the priests were permitted to make this ointment; all others were forbidden to do it on pain of death; see Exodus 30:34-38 (note), and the notes there.

And some of the sons of the priests made the ointment of the spices. For though the Levites had the care of the spices, they might not make the ointment with them, only the priests, see Exodus 30:23.

And of the priests' sons were preparers of the ointments for the spices. It is the preparation from various spices of the holy anointing oil, Exodus 30:23-25, which is meant, and which consequently was part of the priest's duty.

And some of the sons of the priests made the ointment of the spices.

9:30 The ointment - This is added to shew, that though the Levites were intrusted with the keeping of this ointment, yet none but the priests could make it.

9:1-44 Genealogies. - This chapter expresses that one end of recording all these genealogies was, to direct the Jews, when they returned out of captivity, with whom to unite, and where to reside. Here is an account of the good state into which the affairs of religion were put, on the return from Babylon. Every one knew his charge. Work is likely to be done well when every one knows the duty of his place, and makes a business of it. God is the God of order. Thus was the temple a figure of the heavenly one, where they rest not day nor night from praising God, Re 4:8. Blessed be His name, believers there shall, not in turn, but all together, without interruption, praise him night and day: may the Lord make each of us fit for the inheritance of the saints in light.