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.
Know all men by these presents: That we, A. B., of ---------, as principal, and E. F., of---------, as surety, are held and firmly bound unto C. D., of --------in the sum of --------- [here insert penal sum] dollars ($---------), for which payment well and truly to be made we do bind ourselves firmly by these presents.
Dated this --------- day of --------, 19--.
Now, if the said A. B. shall pay all the sums of money to be paid by him as provided in said contract of purchase, promptly, when the same become due, and shall well and faithfully perform and discharge all the agreements and obligations on his part to be performed under said contract, then this obligation to be void; otherwise to remain in full force and effect.
Provided, that any forbearance on the part of the said C. D. toward the said A. B. in respect to his neglect or failure to perform any or all of the said agreements and obligations on his part to be performed, or the extension or extensions, by the said C. D. of the time or times of any or all of said payments, shall not in any manner operate to release or discharge the said E. F. from his liability under the above obligation.
In witness whereof, etc.