Numbers 8:24-26

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  24 H3881 This is it that which pertaineth to the Levites: H6242 from twenty H2568 and five H8141 years H1121 old H4605 and upward H935 [H8799] they shall go in H6633 H6635 [H8800] to wait H5656 upon the service H168 of the tent H4150 of meeting
  25 H1121 And from the age H2572 of fifty H8141 years H7725 [H8799] they shall cease H6635 waiting H5656 upon the service H5647 [H8799] of it, and shall serve no more:
  26 H8334 [H8765] But shall minister H251 with their brethren H168 in the tent H4150 of meeting H8104 [H8800] to keep H4931 the charge, H5647 [H8799] and shall do H5656 no service. H6213 [H8799] Thus shalt thou do H3881 to the Levites H4931 concerning their charge.