Praise be to Allah.
Firstly: if jihad is fard ‘ayn (an individual obligation), as in the circumstances that are explained in sharee’ah, then whoever owes a debt should go out for jihad and he does not have to seek permission from the person to whom he owes that debt.
If the jihad is fard kifaayah (a communal obligation) such as offensive jihad, then it is not permissible to go out except with the permission of the person to whom he owes that debt; if he gives him permission then he may go out, otherwise he should not, unless he leaves enough to pay off the debt or leaves something in pledge with him or he asks someone else to acts as his guarantor, in which case he does not need the permission of the creditor.
For more information on the rulings on jihad and when it is an individual obligation and when it is a communal obligation, please see question no. 34830.
Ibn Qudaamah (may Allaah be pleased with him) said in al-Mughni (13/28): “Whoever owes a debt that is due to be paid now or at some time in the future, it is not permissible for him to go out to fight except with the permission of his creditor, unless he leaves behind enough to pay it off or leaves something in pledge with him or he asks someone else to acts as his guarantor. This is the view of al-Shaafa’i.
The evidence for that is that a man came to the Messenger of Allaah (peace and blessings of Allaah be upon him) and said: O Messenger of Allaah, if I am killed for the sake of Allaah, and bear that with patience, seeking the reward of Allaah, will that expiate for my sins? He said: “Yes, except for debt. Jibreel told me that.” Narrated by Muslim.
That is because what is sought in jihad is martyrdom in which a person loses his life, and the rights and dues of others are lost as a result.
But if it is a case where jihad becomes an individual obligation, then he does not need the permission of his creditor, because it is the matter of individual obligation, which takes precedence over other duties, as in the case of all other individual obligations.
If he leaves behind enough to pay it off or asks someone to act as his guarantor, then he may go and fight without (his creditor’s) permission. This was stated by Ahmad concerning one who leaves behind enough to pay it off. That is because ‘Abd-Allaah ibn Haraam, the father of Jaabir ibn ‘Abd-Allaah, went out to Uhud, and he owed a great debt. He was martyred and his son paid off his debt, with the knowledge of the Prophet (peace and blessings of Allaah be upon him), and the Prophet (peace and blessings of Allaah be upon him) did not criticize him for that, rather he praised him and said: “The angels continued to shade him with their wings, until you lifted him (from the battlefield).” And he said to his son Jaabir: “Do you know that Allaah brought your father to life and spoke to him directly?”
Its says in al-Mawsoo’ah al-Fiqhiyyah (16/135):
But if jihad becomes an individual obligation, there is no dispute among the scholars that there is no need for permission from the creditor.”
Secondly: In the event that the debtor has enough money to pay off the debt, does going out for jihad take precedence, or paying off the debt?
The answer is that if jihad is a communal obligation, then paying off the debt takes precedence, but if jihad is an individual obligation, then one of the following two scenarios must apply:
1-If jihad is an individual obligation because he has joined the ranks of the mujaahideen, or the enemy has come to his land, then jihad must take precedence.
2-If jihad is an individual obligation because the ruler has asked him to go out for jihad, then paying off the debt must take precedence.
Shaykh al-Islam said in al-Ikhtiyaaraat (p. 308):
I was asked about a man who owed a debt and had enough to pay it off, but jihad had become an individual obligation for him. I said:
There are some duties that take precedence over paying off a debt, such as spending on oneself, one's wife and one's poor son. And there are some which are superceded by the obligation to pay off a debt, such as acts of worship like Hajj and expiations. And there are some which supercede it unless the creditor is asking for his money, such as sadaqat al-fitr. If jihad becomes an individual obligation in order to ward off harm, such as if the enemy has come (to where he is) or he has joined the ranks of the mujaahideen, then it takes precedence over paying off his debt, as in the case of spending (on himself and his family), and more so. If he is asked to go out for jihad by the ruler, then paying off his debt takes precedence, because the ruler should not ask a debtor to go out for jihad if he is able to do without him. Hence I say that if there is not enough money to feed the hungry and wage jihad without which harm will be caused, then jihad must take precedence even if the hungry people die.
I also say that if the creditors are engaged in jihad by spending the money that they are asking the debtors to pay, then the debts must be paid off, so as to achieve two aims: paying off debts and engaging in jihad. The texts of Imam Ahmad are in accordance with what I have written.