勿以惡小而為之 [－－恶－－为－]

Jyutping mat6 ji5 ok3 siu2 ji4 wai4 zi1
Pinyin wù yǐ è xiǎo ér wéi zhī

Definitions (Wiktionary)
  1. proverb
    Do not commit an evil act just because it is small in scale.