The phrase “let sleeping dogs lie” is a reminder not to bring unnecessary risks or dangers on oneself. The saying originates from the idea that waking up a sleeping dog was dangerous, especially if it was done suddenly. This applies to a greater extent to guard dogs that, once awakened, would likely attack. The phrase has come to be applied to a wide range of situations in which one could prick something that is better left alone.
This etymology is missing or incomplete. Please add or comment on it in the Etymology scriptorium. Luckily, this proverb is less confusing than some, as readers can come to some conclusions about what happens if you don't let a sleeping dog sleep. Let Sleeping Dogs Lie (the present simple third-person singular allows dogs to sleep, the present participle that lets sleeping dogs lie, the simple past and past participle lets dogs sleep) Sir Robert may have been in the habit of advising caution in political politics but, by what the evidence shows, he didn't coin or even use the expression 'let sleeping dogs lie'.
American definition and synonyms of let sleeping dogs lie from the Macmillan Education online English dictionary. Later in the 14th century, it was used by Geoffrey Chaucer in one of his books that says it's good to avoid waking a sleeping dog. They are phrases that act as advice and it takes context and experience to understand what exactly someone means by “letting sleeping dogs lie”. However, the quote seems to be the first time the published proverb “let sleeping dogs lie” has been used.
Imagine that you approach a sleeping dog, you must think that the dog does not pounce on you or bite you, so it would be better to leave it sleeping.