无大无小

no matter how big or small / not distinguishing junior and senior

see 大夫[dai4 fu5]

big; large; great / older (than another person) / eldest (as in 大姐[da4 jie3]) / greatly; freely; fully / (dialect) father / (dialect) uncle (father's brother)

small / tiny / few / young

not to have / no / none / not / to lack / un- / -less