Is the priority to pay off a debt that has been due for ten years, or to save for marriage while paying off the debt in installments?

Our advice to you is to speak with your friend and ask his permission to delay the repayment until the time you desire. If he agrees willingly, then there is no blame upon you. Some scholars have mentioned that borrowing for the purpose of marriage, when there is a need, is recommended because Allah Almighty guarantees its fulfillment. Al-Tirmidhi, Al-Nasa'i, and Ibn Majah narrated: "There are three whom Allah Almighty is duty-bound to help: the mukatab (slave who has a contract of manumission) who desires to pay off his freedom, the one who marries seeking chastity, and the fighter in the cause of Allah Almighty."

However, if your friend does not agree to delay the repayment, then you must hasten to repay the debt. If the debt has a specific due date, some scholars have held that repayment is obligatory even if the creditor does not demand it.