ब्राह्मणोदकुम्भाग्निसकाशे साक्षिणः परिगृह्णीयात् ॥ कZ_०३.११.३४ ॥
brāhmaṇodakumbhāgnisakāśe sākṣiṇaḥ parigṛhṇīyāt
Witnesses should be received (and sworn) in the presence of a Brāhmaṇa, a water-jar, and fire.
It increases perceived moral and social cost of lying, strengthening compliance where forensic verification is limited.