Revelation 12:10-11 KJV
And I heard a loud voice saying in heaven, Now is come salvation, and strength, and the kingdom of our God, and the power of his Christ: for the accuser of our brethren is cast down, which accused them before our God day and night. [11] And they overcame him by the blood of the Lamb, and by the word of their testimony; and they loved not their lives unto the death.
The brethren (Body of Christ) overcome Satan by Jesus's blood (his life) and their testimony that Jesus raised from the dead and paid for ALL our sins, and is documented in that they care more about Jesus than themselves.
Richard, I would be surprised if this was what you are thinking of, but I would not be surprised if it coincides with what you are thinking of.