C. F. Keil and Franz Delitzsch on 1 Chronicles 23:31

1Ch 23:31 “And for all the bringing of offerings to Jahve on sabbaths, the new moons, and the feasts, in the number according to the law concerning them (i.e., according to the regulations that existed for this matter), continually before Jahve.” It was the duty of the Levites to procure the necessary number of beasts for sacrifice, to see to their suitableness, to slaughter and skin them, etc. תּמיד refers to עלות, the burnt-offerings for Jahve, which are תּמיד, because they must always be offered anew on the appointed days.