to not talk about things which have caused problems in the past, or to not try to change a situation because you might cause problems.

His parents never referred to the shoplifting incident again. I suppose they thought it best to let sleeping dogs lie.

It wasn't that we didn't want to improve the school - it was more a case of letting sleeping dogs lie.

• have pity on someone
• have pride of place
• have rolling in the aisles
• have second thoughts
• have seen better days
• have seen more something than has had hot dinners
• have seen more something than someone has had hot dinners
• have seen more than has had hot dinners
• have seen more than someone has had hot dinners
• have seen the last of
• have seen the last of someone
• have seen the last of something
• have several strings to bow
• have several strings to your bow
• have share of
• have share of something
• have shit for brains
• have sights set on
• have sights set on doing something
• have sights set on something
• have someone by the balls
• have someone by the short and curlies
• have someone dead to rights
• have someone down on like a ton of bricks
• have someone down on you like a ton of bricks