English equivalent: Conceal not the truth from thy physician and lawyer.
This old Latin Proverb drives home the fact that in most cases it would be best to tell the whole truth, especially with your doctor and councilor - but even more so, you should always strive to tell the truth no matter who you are dealing with, because then you don't have to keep the story straight, since any one can always go back to the source and verify you told the truth!!!
