God questioned Cain,
“What have you done? The voice of your brother’s blood cries out to Me from the ground” (Genesis 4.10).
Cain killed his brother and the blood of Abel cried out to God from the ground. That brought God into the picture to deal with Cain’s sin.
Then in the New Testament, the Bible makes this declaration, saying that we have come,
“to Jesus the Mediator of the new covenant, and to the blood of sprinkling that speaks better things than that of Abel” (Hebrews 12.24).
Genesis established the fact that spilled blood cries out to God, crying out to Him for vengeance, but in Hebrews, while the blood still calls out, the blood of Christ in this case cries out to God for forgiveness!