Dictionary of Biblical Words:
This means one who is taking the responsibility due to another, as in endorsing a bill of exchange, &c. Christ is thus the sinner’s surety, taking upon Himself all the responsibility of his sine, and answering to God for them all. Humanly speaking suretyship is condemned (see Prov. 11:15), but without a Divine surety we all were lost.
Boyd’s Bible Dictionary:
(security). Suretyship in the older sense of pledge was regulated by the Mosaic law (Gen. 44:32; Ex. 22:25-26; Deut. 24:6-17). When Solomon opened Palestine to commerce, suretyship took the forms of general law and trade (Prov. 6:1; 11:15; 17:18; 20:16; 22:26). [LOANS.] [PLEDGE.]