Whatever is well said by another, is mine.

Seneca the Younger (c. 4 BC-AD 65) Roman statesman, philosopher, playwright [Lucius Annaeus Seneca]

Moral Letters to Lucilius [Epistulae morales ad Lucilium], letter 16 “On Philosophy, the Guide of Life,” sec. 7

Alt. trans.: "Whatever is well said by anyone is mine." [tr. Gummere (1918)]