言わずもがな

Consisting of 言わず (“not saying”) +‎ も (“even if”) +‎ がな (“particle used to indicate the speaker's hope, desire, wish”)

言(い)わずもがな • (iwazumogana) 

1. not even saying would be preferable (because not expressing it at all would be better)

   言(い)わずもがなのことを言(い)う

   iwazumogana no koto o iu

   saying unnecessary things (that would be better if left unsaid)

2. needless to say, not to mention, obvious (because it is already known)

   子供(こども)は言(い)わずもがな、大人(おとな)まで騒(さわ)ぎ出(だ)した。

   Kodomo wa iwazumogana, otona made sawagidashita.

   Even the adults were panicking, not to mention the children.

   Synonym: 言うまでも無い