In this case, the covenant is God's words or laws that he gave Moses to spread to the people. The book of Exodus says, "And Moses took half of the blood, and put it in basons; and half of the blood he sprinkled on the altar. And he took the book of the covenant, and read in the audience of the people: and they said, All that the Lord hath said will we do, and be obedient. And Moses took the blood, and sprinkled it on the people, and said, Behold the blood of the covenant which the Lord hath made with you concerning all these words" (Exodus 24:6-8 KJV). Once the people of Israel said they would obey, Moses used the oxen blood to sprinkle onto the altar and the people as a blessing.
In these times, sacrificing an animal was a sacred act. Using the blood of a sacrificed animal was a distinctive way for Christians to bless one another. It was a sign of washing away sins. However, it was used in such a way that it would not enter the body of a human being. Consuming the blood of an animal was considered an abomination. As said by the Dictionary of mythology Folklore and Symbols by Gertrude Jobes, "In Christian tradition, martyrdom, Christ. Ancient Hebrews believed it was the seat of life to God, and for this reason taboo as food" (Jobes 226). Having the blood of an animal was essential in the Christian tradition. Using the blood for certain purposes such as blessings, frequently brought people closer to God. Since Moses had sprinkled the people of Israel with blood, the sins of the Israelites were washed away.
In the book of Mark, blood is also associated with purity and blessings. During The Last Supper, Jesus took bread and divided it. After giving thanks to it, he passed the pieces of bread to the disciples and told them it was represented his body. Jesus did the same with a cup of wine and passed it around to everyone. He told the disciples, "Verily I say unto you, I will drink no more of the fruit of the vine, until that day that I drink it new in the kingdom of God" (Mark 14:25 KJV).
