Keep your enemies closer?

Attributed to several authors, it apparently was a Sun Tzu council about war.

It is as wrong as it is popular.

Ecclesiasticus 12

[10] Never trust thy enemy: for as a brass pot his wickedness rusteth: 

[11] Though he humble himself and go crouching, yet take good heed and beware of him. [12] Set him not by thee, neither let him sit on thy right hand, lest he turn into thy place, and seek to take thy seat: and at the last thou acknowledge my words, and be pricked with my sayings. [13] Who will pity an enchanter struck by a serpent, or any that come near wild beasts? so is it with him that keepeth company with a wicked man, and is involved in his sins. [14] For an hour he will abide with thee: but if thou begin to decline, he will not endure it. [15] An enemy speaketh sweetly with his lips, but in his heart he lieth in wait, to throw thee into a pit. 

[16] An enemy weepeth with his eyes: but if he find an opportunity he will not be satisfied with blood: [17] And if evils come upon thee, thou shalt find him there first. [18] An enemy hath tears in his eyes, and while he pretendeth to help thee, will undermine thy feet. [19] He will shake his head, and clap his hands, and whisper much, and change his countenance.