千金の裘は一狐の腋に非ず (hiragana せんきんのきゅうはいっこのえきにあらず, romaji senkin no kyū wa ikko no eki ni arazu)
From Literary Chinese. Literally "an expensive fur garment is not done with the armpit of one fox". From 史記, where it appears as "千金之裘，非一狐之腋".