1-chronicles 23:31
Translations
King James Version (KJV)
And to offer all burnt sacrifices to the LORD in the sabbaths, in the new moons, and on the set feasts, by number, according to the order commanded to them, continually before the LORD:
American King James Version (AKJV)
And to offer all burnt sacrifices to the LORD in the sabbaths, in the new moons, and on the set feasts, by number, according to the order commanded to them, continually before the LORD:
American Standard Version (ASV)
and to offer all burnt-offerings unto Jehovah, on the sabbaths, on the new moons, and on the set feasts, in number according to the ordinance concerning them, continually before Jehovah;
Basic English Translation (BBE)
At every offering of burned offerings to the Lord, on Sabbaths, and at the new moons, and on the regular feasts, in the number ordered by the law, at all times before the Lord;
Webster's Revision
And to offer all burnt-sacrifices to the LORD on the sabbaths, in the new moons, and on the set feasts, by number, according to the order commanded to them, continually before the LORD:
World English Bible
and to offer all burnt offerings to Yahweh, on the Sabbaths, on the new moons, and on the set feasts, in number according to the ordinance concerning them, continually before Yahweh;
English Revised Version (ERV)
and to offer all burnt offerings unto the LORD, in the sabbaths, in the new moons, and on the set feast, in number according to the ordinance concerning them, continually before the LORD:
Barnes's 1-chronicles 23:31 Bible Commentary
Though the Levites were not allowed by themselves to offer sacrifice, yet there were many respects in which they assisted the priests when sacrifice was offered. See 2 Chronicles 29:34; 2 Chronicles 35:11-12.
The set feasts - The Passover, Feast of Pentecost, and Feast of Tabernacles (marginal reference).