知己知彼，百战不殆 (知己知彼，百戰不殆) zhījǐ zhī bǐ, bǎi zhàn bù dài

zhījǐ zhī bǐ, bǎi zhàn bù dài phrase know yourself and know your enemy, and you will never be defeated
Domain: Modern Chinese 现代汉语
Notes: From Sunzi's The Art of War 孙子兵法 (CC-CEDICT '知己知彼，百戰不殆')