相安無事

First attested in c. 1300 in Deng Mu's The Way of Officials:

古者軍民間相安無事，固不得無吏，而爲員不多。唐虞建官，厥可稽已，其去民近故也。 [Literary Chinese, trad.]
古者军民间相安无事，固不得无吏，而为员不多。唐虞建官，厥可稽已，其去民近故也。 [Literary Chinese, simp.]

From: c. 1300, 鄧牧,《伯牙琴·吏道》

Gǔzhě jūnmín jiān xiàng'ānwúshì, gù bùdé wú lì, ér wéi yuán bùduō. Táng-Yú jiàn guān, jué kě jī yǐ, qí qù mín jìn gù yě. [Pinyin]

In ancient times, the military and the people coexisted peacefully. Officials were no doubt indispensable, yet their numbers were not many. The official posts established during the reigns of Yao and Shun are well-documented and verifiable. This was because Yao and Shun remained close to the people.

相安無事

1. to coexist peacefully