What is the exact phrase of Shakespeare’s for the phrase meaning “It’s not yet the worst when you are saying it’s the worst (situation).”?

I once posted a question in this forum asking what is the counterpart saying to Japanese proverb, “There’s no wild pig larger than the mountain (from where it emerges)” and am thankful for receiving many answers from users.

Today I found the quote from Shakespeare’s work to the effect of “It’s not yet the worst when you are saying you are in worst situation” in “Vox Populi, Vox Dei,” a columnist’s column of the Asahi newspaper. The essay simply says it from Shakespeare, and doesn’t show English text of the phrase, nor what part of Shakespeare’s work it came from.

After experiencing the M-9 earthquake and tsunami that devastated coastal and inland area of Eastern Japan, and watching many people going through tough time before our eys, I keep telling myself and others, “My heart goes out to you, but believe me, “There’s no wild pig larger than the mountain.”

Can somebody tell me the exact wording, and what work of Shakespeare this axiom quoted in “the Vox Populi, Vox Dei,” came from?

I'll hazard a guess that it's from King Lear:

"And worse I may be yet: the worst is not So long as we can say 'This is the worst."