台Taivo A Taiwan Mandarin dictionary

一塵不染

yīchénbùrǎn

ㄧㄔㄣˊ ㄅㄨˋ ㄖㄢˇ

Simplified 一尘不染

1(idiom) untainted by even a speck of dust; spotlessly clean; (of a person) honest; incorruptible

Keep 一塵不染 and it comes back until you know it.