台Taivo A Taiwan Mandarin dictionary

知己知彼，百戰不殆

zhījǐzhībǐ,bǎizhànbùdài

ㄓㄐㄧˇ ㄓㄅㄧˇ , ㄅㄞˇ ㄓㄢˋ ㄅㄨˋ ㄉㄞˋ

Simplified 知己知彼，百战不殆

1know yourself and know your enemy, and you will never be defeated (idiom, from Sunzi's "The Art of War" 孫子兵法|孙子兵法[Sun1 zi3 Bing1 fa3])

Keep 知己知彼，百戰不殆 and it comes back until you know it.