心照不宣

心照不宣 [xīn zhào bù xuān]

1. ■ Both understand from their hearts what the matter is but do not choose to say so in public.; have a tacit (mutual) understanding; no need to express oneself in so many words; no need to say how grateful (I am); not necessary to say more; think it is not necessary to say more; thoroughly understand each other, without having exchanged a word of explanation; take wordless counsel