This law is both useful and serves as a warning. It is most powerful when you’re creating relationships with the mistrustful. While they may eye your approach with distrust, read on to learn the strategy to win them over. 
Conversely, beware the enemy who comes bearing gifts. Think once, think twice and then, think again.
~ Courtesy of The 48 Laws of Power by Robert Greene
In ancient China, Duke Wu of Chenge decided it was time to take over the increasingly powerful kingdom of Hu. Telling no one of his plan, he married his daughter to Hu’s ruler. He then called a council and asked his ministers, “I am considering a military campaign. Which country should we invade?” The duke seemed angry and said, “Hu is a sister state now. Why do you suggest invading her?” He had the minister executed for his impolite remark. The ruler of Hu heard about this and considering other tokens of Wu’s honesty and the marriage of his daughter, he took no precautions to defend himself from Chenge. A few weeks later, Cheng forces swept through Hu and took the country, never to relinquish it.
Honesty is one of the best ways to disarm the wary, but it is not the only one. Any kind of noble, apparently selfless act will serve. Perhaps the best such act, though, is one of generosity. Few people can resist a gift, even from the most hardened enemy, which is why it is often the perfect way to disarm people. A gift brings out the child in us, instantly lowering our defenses. Although we often view other people’s actions in the most cynical light, we rarely see the Machiavellian element of a gift, which quite often hides ulterior motives. A gift is the perfect object in which to hide a deceptive move.