Dictionary.net

• The verse formerly read to entitle the person to benefit of clergy-said to be the first of the 51st Psalm.

1899 - The american dictionary of the english language.
By Daniel Lyons

• The verse anciently required to be read by a criminal to entitle him to benefit of clergy, said to be the beginning of the 51st Psalm.

1874 - Etymological and pronouncing dictionary of the English language
By Stormonth, James, Phelp, P. H.