Legal analysis: You are the guarantor. Your friend didn't pay off the loan within the prescribed time limit, and you didn't bear joint responsibility to help him pay off the loan. If you do this, your credit history will be affected, which will lead to blacklist.

Legal basis: Article 394 of the Civil Law of People's Republic of China (PRC) guarantees the performance of debts. If the debtor or a third party mortgages the property to the creditor without transferring the possession of the property, the debtor fails to perform the due debt or the creditor has the right to receive priority compensation for the property. The debtor or the third party specified in the preceding paragraph is the mortgagor, the creditor is the mortgagee, and the property that provides guarantee is the mortgaged property.