We often give our enemies the means for our own destruction

Enemies' promises were made to be broken

Self-conceit may lead to self destruction.

Thus the Jews smote all their enemies with the stroke of the sword, and slaughter, and destruction, and did what they would unto those that hated them.

The haft of the arrow had been feathered with one of the eagles own plumes. We often give our enemies the means of our own destruction.

A doubtful friend is worse than a certain enemy. Let a man be one thing or the other, and we then know how to meet him.