(the) truth will out British old-fashioned
You shouldn't lie because the truth will out in the end.
Everybody knew Tony stole company documents because the truth will out in the end.
He is trying to hide the fact that he has an affair but the truth will out sooner or later.
Time keeps passing.
White lie
To tell someone the truth about something that they had not understood or received false information
This phrase comes from Shakespeare's The Merchant of Venice, 1596:
LAUNCELOT: Nay, indeed, if you had your eyes, you might fail of the knowing me: it is a wise father that knows his own child. Well, old man, I will tell you news of
your son: give me your blessing: truth will come to light; murder cannot be hid long; a man's son may, but at the length truth will out.