The ritual for the first use of the meeting place and it fixtures, and for ordaining Aaron and his sons (the priests), was to be complex, theatrical and, to our eyes, involved a lot of handwashing, meat and fat burning, and blood.
Several animals were slaughtered, their blood splashed and dabbed around; their meat, fat and entrails were burned. Some aspects of this ritual were to be completed each year. Some, such as the handwashing, were to be completed every time the priests approached the altar.
It sounds repulsive to a 21st-century city dweller: blood splashed on the altar, on the sides of the altar, on the priests’ clothes; blood dabbed on bits of the altar and on the right earlobe, thumb and big toe of the each of the priests. Blood everywhere. Without explanation.
The Israelites’ most recent experience with dabbing and splashing blood was just after Moses read out the ten commandments and the regulations to the Israelites:
24:8 Look, this blood confirms the covenant the Lord has made with you in giving you these instructions.
And before that, on the night of the Passover, when God came to execute judgment against all the gods of Egypt:
Exodus 12:23 Then brush [the blood of a slaughtered lamb] across the top and sides of the doorframes of your houses. For the Lord will pass through the land to strike down the Egyptians. But when he sees the blood on the top and sides of the doorframe, the Lord will pass over your home.
The blood now served the same purpose: to confirm God’s promise that He would keep the Israelites safe from a similar death-by-judgement. It is hard to believe that Moses, and later the Israelites when the first priests were ordained, would not have associated the recent events with these commands for ritual purification.
As God did in Egypt, it would become a very visual object lesson: only those without sin can approach God and live.
There is no explanation: nothing to say why there was so much blood and why it would be dabbed on ears, thumbs and toes; it is more concerned with the what at this point. Some people have suggested that this part of the ritual represents how we should listen, serve and walk: everything we do should be clean from sin and ready to pass on the holiness of God.