5 In the Law Moses commanded us to stone such women. Now what do you say?” 6 They were using this question as a trap, in order to have a basis for accusing him. But Jesus bent down and started to write on the ground with his finger. 7 When they kept on questioning him, he straightened up and said to them, “Let any one of you who is without sin be the first to throw a stone at her.” 8 Again he stooped down and wrote on the ground.

Story says he knew how to write (historically, more dubious)