It becomes the responsibility of Aaron and his sons to serve the LORD; to come between the people and YHWH; to bring the people, their requests, their need for cleansing to the LORD. As such Aaron and his sons needed to have one foot on the earth, and the other in the doorway to heaven. How do you balance the impurity and sin that is so prevalent in the world with the awesome purity and Holiness of God? Talk about a difficult task; yet that is what Aaron and his sons are charged with doing.
The first steps in fulfilling that role are described here. Before anything else, Aaron and his sons need to be separated from the group and cleansed both physically and spiritually. They are responsible for being representatives / ambassadors / spokesmen of men to God. Therefore in coming into God’s presence they must be as close to clean and pure as humanly possible. So in this process, Moses is responsible to follow YHWH’s instruction and purify Aaron and his sons.
Could you imagine having the responsibility of being the one that stands between man and YHWH? Every day you must perform your duties and bring the sacrifices and offerings of the people before Him. Thus the process of being set apart for God is extremely important.
One thing of interest that i did note, in these first 25 verses of Exodus 29, is that in verse 22 it talks about taking the fat from the ram and from all of these different parts, and then it says, “and the right thigh (for it is a ram of ordination)“. When i was looking at this, i thought it was kind of weird that it said to take the fat from the kidneys, and the fat from the entrails, and the fat tail, etc. and then randomly talked about the right thigh because it is a ram of ordination.
It does seem kind of strange, but not so much when you refer back to Genesis 32:24-32. This passage in Genesis is where Jacob, who had been blessed and set apart by God, wrestles with God. God touches his thigh socket and he has a limp from then on, and the sons of Jacob do not touch the sinew of the thigh of the meat that they eat. It is an interesting parallel. I don’t know beyond a doubt that this is what this is referring to, but it sure does give you pause to think.