बन्धुमुख्यप्रग्रहः प्रतिग्रहः ॥ कZ_०७.१७.११ ॥
bandhu-mukhya-pragrahaḥ pratigrahaḥ
A ‘counter-pledge’ (pratigraha) is the taking/holding (pragraha) of a kinsman or a principal (leading person).
It creates enforceable reciprocity: by holding a high-value person, the state gains leverage to deter breach and to compel performance without immediate war.