I Chronicles 25:10 Midrash

הַשְּׁלִשִׁ֣י זַכּ֔וּר בָּנָ֥יו וְאֶחָ֖יו שְׁנֵ֥ים עָשָֽׂר׃

The third to Zaccur, his sons and his brethren, twelve;