fail to report the facts
It is an idiom to know the inside story without exposing it. Now, it is often pointed out that people who know other people's crimes do not expose them to relevant organizations and judicial organs.
source
In the first chapter of the complete biography of the flying dragon by Wu Xuan in the Qing Dynasty, "I'm a city inspector, so I'd like to hear about it. If I'm a friend, I'll be accused of not giving it up."
Examples
After hearing that he even participated in the impeachment, he said that he was guilty of cheating. He knew that he was inconvenient, and he closed the door tightly. The 36th chapter of Huang Xiaopei's twenty year dream of prosperity in Qing Dynasty.
fail to report the facts
be very hard up , and in fact ) be at a loose end - shí guāi yùn guāi
the army is completely wiped out - piàn jiǎ bù cún
The tiger scratched its head - lǎo hǔ tóu shàng sāo yǎng