This section is from the book "The Law Of Contracts", by William Herbert Page. Also available from Amazon: Commercial Contracts: A Practical Guide to Deals, Contracts, Agreements and Promises.
If the creditor stands upon his rights and waives none of them, he may insist upon the debtor's strict compliance with the elements of tender. Only the debtor, or his legal representative,1 can make a valid tender. The creditor may refuse a tender by a stranger, without incurring any legal liability,2 though if he accepts such payment or performance he is concluded thereby. An exception to this rule exists in cases where a person financially interested in the discharge of a debt,3 such as a surety,4 or the owner of realty upon which such debt is a lien,5 as the owner of mortgaged premises,8 or an assignee in bankruptcy,7 tenders payment of such debt. Such tender is valid.