Slaughter it, take some of its blood and put it on the lobes of the right ears of Aaron and his sons, on the thumbs of their right hands, and on the big toes of their right feet. Then splash blood against the sides of the altar.
This was part of the consecration ceremony for Aaron and his sons, as priests set apart to serve God in the tabernacle. The marking of the right ear lobes reminds me of this other passage:
But if the servant declares, ‘I love my master and my wife and children and do not want to go free,’
In both instances, we see that they were willing to serve their masters (God, in Aaron’s case, and the human master in the slave’s case) and the earmarking was a sign of who they belonged to. Also, it was a lifelong commitment. In addition, the earmark was clearly visible for everyone to see.
In the same way, when we are willing to give our lives to God, we are earmarked and set apart for life, regardless of our age and station in life. Our words and actions are to make Christ constantly visible to the world, wherever He places us and not only when we are serving in church or on the mission field. As for prodigals who stray away, like the lost sheep (in Matthew 18:12-14 and Luke 15:3-7), God will not lose sight of His mark on them and will pursue them all their lives until they return to the fold.
Incidentally, sheep are also earmarked as a sign of ownership. Like sheep, we are set apart for our Shepherd’s Purpose, consecrated like Aaron to fulfil His destiny for us. Perhaps God chose the ear to be marked as a reminder of the need for us to pay heed to the Master's instructions and to respond, "Not my will but Yours be done." We are also under His Protection, and He will watch over us and keep us from harm, from the lion and the bear (1 Samuel 17:34-35), and from the thief who comes to steal, kill and destroy (John 10:10). Even when death and destruction strike, we will be Preserved forever and enjoy eternal life with Him. And with The Lord as our Shepherd, we shall lack nothing (Psalm 23:1) for His Provision for us is always sufficient and timely.
That’s why we can say most confidently:
Whoever dwells in the shelter of the Most High will rest in the shadow of the Almighty. I will say of the Lord, “He is my refuge and my fortress, my God, in whom I trust.”