“¶ These were the sonnes of Leui after the house of their fathers, euen the chiefe of the fathers, as they were counted by number of names by their polles, that did the worke for the seruice of the house of the Lord, from the age of twentie yeeres and vpward.”
1611 King James Version (KJV)
23:24 Twenty years - As the Levites were anciently numbered fromtwo several times, from the twenty fifth year of their age, and from thethirtieth, #Numb 4:3 8:24|. In like manner they are here numbered bothfrom their twentieth year, when they were solemnly prepared for, andinstructed, and by degrees exercised in some parts of their work; andfrom their thirtieth year, when they were admitted to the full exerciseof their office. And the reason why they were now sooner admitted toservice than they had been formerly, is given in the next verses becausenow their work was more easy, being wholly discharged from that burdensomework of carrying the tabernacle. Besides the people of Israel weremultiplied: therefore more hands were necessary, that every Israelitewho brought an offering, might find a Levite ready to assist him.