„If your enemy is secure at all points, be prepared for him. If he is in superior strength, evade him. If your opponent is temperamental, seek to irritate him. Pretend to be weak, that he may grow arrogant. If he is taking his ease, give him no rest. If his forces are united, separate them. Attack him where he is unprepared, appear where you are not expected.“
— Sun Tzu
"If his forces are united, separate them" is also interpreted: "If sovereign and subject are in accord, put division between them."
Original: (zh_Hant) 實而備之，強而避之，怒而撓之，卑而驕之，佚而勞之，親而離之，出其不意，攻其不備。
Source: The Art of War, Chapter I · Detail Assessment and Planning