When Genghis Khan laid siege to Bukhara, he could not take it by storm, so he wrote to the inhabitants of the city: “He who is on our side is safe.” The inhabitants of Bukhara were divided into two groups. The first of them refused to obey Genghis Khan, while the second agreed. Genghis Khan wrote to those who agreed to submit to him: “If you help fight those of you who refused, we will entrust your city to you.”

So they followed his order and war broke out between the two groups. In the end, the “supporters of Genghis Khan” won, but the big shock was that the conquerors took up arms and began to kill them. And then Genghis Khan uttered the words:

“If they were true, they would not have betrayed their brothers for us, when we were strangers to them"

Moral: He who betrays once, betrays him twice.”

Arab historian Ibn al-Athir (1160-1234).