let sleeping dogs lie
/ˌlet ˌsliː.pɪŋ ˈdɒɡz ˈlaɪ/idiom
to avoid talking about a past problem in order not to cause new trouble
не будить лихо, не ворошить прошлое
Русский аналог: «не буди лихо, пока оно тихо»
Глагол lie — «лежать», а не lay. Обычно как совет: Just let sleeping dogs lie.
“I wanted to ask about the argument, but decided to let sleeping dogs lie.”
“It happened years ago — let sleeping dogs lie.”
“Sometimes it’s wiser to let sleeping dogs lie.”