Kautilya's Arthashastra 7.9.48

7.9.48

arer netuś ca yad vṛddhiṃ daurbalyād anuvartate /
ubhayasyāpy avidviṣṭaṃ vidyād ubhayabhāvi tat //

whoever, owing to his own weakness, follows the ascendancy of both the conqueror and his enemy, not incurring enmity with either, is known as a common friend;