Who would be the high priests in every generation for Israel? The Lord showed Israel that they did not have to worry about that,
“Aaron and his sons offered sacrifices on the altar of burnt offering and on the altar of incense, for all the work of the Most Holy Place, and to make atonement for Israel, according to all that Moses the servant of God had commanded. Now these are the sons of Aaron…” (1 Chronicles 6:49-53).
The Lord thinks of everything. When He commands something to be done, He provides the tools, knowledge, wisdom, and resources. Therefore, even as the sons of Aaron did what the Lord told them do, let us do what the Lord has told us to do, and He shall make sure that we can do it.