一山不容二虎 (yì shān bù róng èr hǔ)

一山不容二虎

(yì shān bù róng èr hǔ)
English Translation:“One mountain cannot contain two tigers.”

Meaning:
Two people are incompatible in some way, and conflict is inevitable when they are together. This is used to describe situations where two strong personalities or rivals clash.

Example:
他们俩总是争论不休，一山不容二虎。
(The two of them always argue; “one mountain cannot contain two tigers.”)

Source: Hello Mandarin