Kautilya's Arthashastra 7.9.46

7.9.46

priyaṃ parasya vā rakṣyaṃ pūjyaṃ sambaddham eva vā /
anugṛhṇāti yan mitraṃ śatrusādhāraṇaṃ hi tat //

whoever helps the enemy's friend, protege, or any vulnerable person or a relation of the enemy is a friend common to (both) the enemy (and the conqueror);