expression
white lie; harmless lie; fib
A lie told to avoid hurting someone's feelings or to smooth a social situation, without malicious intent.
彼女は罪のない嘘をついて、友達を傷つけないようにした。
She told a white lie so as not to hurt her friend's feelings.
それはただの罪のない嘘だから、気にしなくていいよ。
It's just a harmless lie, so don't worry about it.
嘘 is a general lie, while 罪のない嘘 specifically refers to a lie without malice or serious consequences.
Phrase composed of 罪 (tsumi, 'sin/crime'), の (possessive particle), ない (negative), and 嘘 (uso, 'lie'), literally 'a lie without sin'.