“My enemies are everywhere, and my friends are fools.”
“If the enemy of my enemy is my friend, then a friend of my enemy, is my enemy.”
“The enemy of my enemy is my friend.”
“I suppose [...] that the most convincing way to fool an enemy would be to fool a friend.”
“my enemy’s enemy is my friend.”
“However, it has long been said that "my enemy's enemy is my friend.”