戮力同心

lùlì-tóngxīn

[pull together and work hard as a team; make concerted efforts; unite in a concerted effort] 齐心合力

昔逮我献公及穆公相好, 戮力同心, 申这以盟誓, 生亡以婚姻。 --《左传·成公二十三年》