Arthashastra
यः सत्य संधः शक्तः कर्मणि फल अवाप्तौ च अनुग्रहीतुं विनिपाते च त्रातुं तत्र प्रतिजापः कार्यः, तर्कयितव्यश् च कल्याण बुद्धिर् उत अहो शठ इति ॥
and in the case of a person who is of reliable character, able to undertake works, and to favour his ally in his success, and to afford protection against calamities, counter-intrigue (pratijápa) should be made use of (to keep his friendship secure). It should also be considered whether the person is of good disposition or of obstinate temper (satha).
english translation
yaH satya saMdhaH zaktaH karmaNi phala avAptau ca anugrahItuM vinipAte ca trAtuM tatra pratijApaH kAryaH, tarkayitavyaz ca kalyANa buddhir uta aho zaTha iti ॥
hk transliteration by Sanscript