In the New Testament, Jesus refers to the use of sackcloth and ashes as signs of repentance: «Woe to you, Chorazin! (religion.blogs.cnn.com)
Remember how the father in the parable «had compassion and ran and embraced him and kissed» the son before there was any chance for him to test the son for signs of repentance. (religion-online.org)
Baptism, as John preached and practiced it, was thus a sign of repentance and forgiveness. (religion-online.org)