Two times in the Bible there is a reference to blood that speaks. What does this talking blood mean? 

The blood of Abel speaks (Genesis 4:3-10). It cries out for justiceness. … Cain and Abel were brothers, children of Adam and Eve. When they brought offerings to God, Abel brought his best and Cain did not. God showed favor towards Abel and Cain grew jealous or upset and killed Abel. God told Cain that his brother's blood called out to Him. This tells us that God knows and he hears when injustice is done. And God doesn't let it go unpunished. Cain was punished for his crime. In some countries today, persecution of Christians is on the rise. God hears their blood. When the Holocaust happened, God heard the blood of the Jews who were murdered. When racial killings happen, God hears that blood too. Every day thousands of abortions happen, and God hears the blood of those babies. All this blood cries out for justice and justice will come.

The blood of Jesus speaks (Hebrews 12:18-24). It cries out for mercy. … This vision contrasts Mount Sinai and Mount Zion. Mount Sinai is where Moses went up and got the Ten Commandments. When he came down, he sprinkled animal blood as a sacrifice to atone for the sins of the people, a process that needed to be repeated regularly. Mount Zion here is used as a metaphor for a heavenly Jerusalem. This scripture provides a picture of who will be in Heaven (on Mount Zion). There will be angels, the church, and Jesus will be there. Sounds like a great place! It also tells us the Blood of Jesus will be sprinkled, like Moses did with the animal blood. But the blood of Jesus is blameless and atones for our sins once and for all. His blood cries out for mercy, a better cry than what the blood of Abel cries for. Through the Blood of Jesus anyone can be saved.