Second Book of Esdras (Author Nehemias or Esdras or both)
13:22I spoke also to the Levites that they should be purified, and should come to keep the gates, and to sanctify the sabbath day: for this also remember me, O my God, and spare me according to the multitude of thy tender mercies.
Original from Project Gutenberg - Massive cleanup of OCR problems and editing done locally.