In
mediaeval England, so
legend goes, a
criminal who was on
trial for his
life could claim "
benefit of clergy". The criminal would then be required to recite a "
trial-verse", namely
Psalm 51:
Have mercy on me, O God, according to thy loving kindness, according unto the multitude of thy tender mercies blot out my transgressions.
... and if the criminal could recite it, his right hand was burned, and then he was set free, thus saving his neck.
If I ever travel back in time to mediaeval England, I am going to memorize this verse first, oh yes.