Rules of Dayn
The Answer
Dayn is any financial liability. It includes loans, debts, buying-selling dues (such as from Salam or Mu'ajaal), etc.
One is not responsible to pay off his Dayn before it is due, nor should he be asked to do so. The only exception is Qard or loan. According to the majority of scholars, someone who lends his money to someone else can ask for his money anytime. Hajr (to stop one from using his money) does not go in effect before the Dayn is due. Once the Dayn becomes due then we look at the financial state of the person with the financial responsibility. If he is poor, then it is incumbent to give him more time. If he is rich and he refuses to pay off the Dayn, then his Ird (honor) becomes Halaal. This means that one can backbite him and complain about him in front of the judge or the ruler in order to get his money back. The judge can put a restrain order against his money [Hajr] and can order to jail him [Habs], because the Prophet said, "the delay of the rich [in paying off his dues] makes his punishment permissible". Dayn does not become due by bankrupcy. At the time of bankrupcy, only the Dayns which are due are to be paid off. Likewise, Dayn does not become due by death as long as the inheritors guarantee the loan by providing a ransom, a kafeel (one who guarantees to bring the person who is financially liable at the time of pay off), or a Daamin (one who guarantees to pay if the financially responsible person does not pay). If a person with a financial liability wants travel and he does not come back until after the Dayn is due, then he can be stopped from his travel unless he guarantees his Dayn by providing either a ransom or a guarantor (Kafeel or Daamin).