Voucher
VOUCHER, noun
1. One who gives witness or full attestation to any thing.
The great writers of that age stand up together as vouchers for each others reputation.
2. In law, the act of calling in a person to make god his warranty of title.
3. A book, paper or document which serves to vouch the truth of accounts, or to confirm
or establish facts of any kind. The merchants books are his vouchers for the correctness of his accounts. Notes, bonds receipts and other writings, are used as vouchers in proving facts.