let slide

Short definition from Wiktionary

Verb

1. 1
   To let go; to allow; to release; to pass over without action.
2. 2
   To pass out of one's thought as not being of any consequence.
3. 3
   To tolerate a violation of a norm from.
4. 4
   To allow the condition of something to deteriorate due to negligence or apathy.
5. 5
   Used other than figuratively or idiomatically: see let, slide.