ДРУЖБА ДРУЖБОЙ, А СЛУЖБА СЛУЖБОЙ (saying) friendly relations should not influence or interfere with official or business relations: = business and friendship (pleasure) don't mixnever mix business and (with) pleasure.
(Кушак:) Они (ваш муж и Зилов) допустили серьезную ошибку в работе. Я бы сказал - непростительную ошибку. (Валерия:) Вот как?.. Так взгрейте их как следует!.. Мужа я прошу наказать со всей строгостью... Каждому - по заслугам... Дружба дружбой, а служба... (Вампилов 5). (К.:) They've (your husband and Zilov have) committed a serious error in their work. An unforgivable error, in my opinion. (V.:) Have they now?...Then give them everything they deserve! Kindly punish my husband with all the severity of the law...They should both get their just desserts....Business and friendship don't mix... (5a).