John Calvin Commentary John 8:13

"The Pharisees therefore said unto him, Thou bearest witness of thyself; thy witness is not true." — John 8:13 (ASV)

The Pharisees therefore said. They present as an objection what is commonly said: that no one should be trusted when speaking in their own cause. For a true testimony signifies “what is lawful and credible.” In short, they mean that it is useless for him to speak, unless he brings proof from some other source.