1 Chronicles 25:9
Now the first lot came forth for Asaph to Joseph: the second to Gedaliah, who with his brethren and sons were twelve: Now the first lot came forth for Asaph to Joseph: the second to Gedaliah, who with his brethren and sons were twelve:
The verse belongs to David's careful organization of the temple musicians. Under that arrangement four thousand musicians were divided into twenty-four courses. Each course was led by twelve men. Those leaders were specially instructed and skilled in playing musical instruments.