Second Book of Esdras (Author Nehemias or Esdras or both)
Chapter 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.