What is the religious obligation regarding one who goes to Afghanistan for a month or two and then returns to his country?

The questioner : The last question: Many of the mujahideen brothers who are not Afghan go to Afghanistan for jihad. Since most of the arrivals are from the Arabian Peninsula, the majority of them stay for a short period, not exceeding a month or two, or even less than a month. A great deal is spent on training them before they enter the jihad and until they reach the frontiers, yet the jihad generally does not benefit from most of them during these short periods, if it is not harmed by them. It is known that most of them have no need for them in their own country or among their families when they return, and they are all strong young men who can bear the burdens of jihad. So what is it that is obligatory upon us religiously regarding these people? May Allah reward you with good.

The Shaykh : I have said—more than once—that anyone who wants to go to Afghanistan to fight in the path of Allah must place himself under the will of the Amir—the Amir of the jihad there. It is not permissible for him to go there to spend a month or two learning the methods of combat that suit him and then return as if he has no authority over him, or no emirate over him. This is not permissible. Rather, he must remain there until the ruler who governs him there says to him: I have no objection to your going and being absent, for example, for a month or two.
As for making the jihad in Afghanistan like a trip that a strong young man goes on to learn the methods of combat, and then returns—just as some of them told me, preparing for the jihad in Palestine—why does he not prepare for fighting in Afghanistan, which is an ongoing jihad, but rather prepares for a jihad that may occur? This is not permissible. Therefore, the true mujahid is the one who adheres to the rulings of the Shari'ah, including obeying the ruler there, and not contradicting him except in what involves disobedience to Allah. This is not of that category; because his going there and staying for two or three months and then returning without the permission of the ruler—especially since the question mentions that these people may spend vast sums of money on these arrivals from Arab countries, money they are in direst need of, and then they return without the jihad there benefiting from them in any way—this is not permissible. In my opinion, the reason for this goes back to two things:
The first thing is that these mujahideen do not know the rulings of jihad. For example, they may take some of the war spoils, which is considered ghalul (embezzlement of spoils), without these spoils being distributed by the responsible party there. They think that this is permissible. So the first thing goes back to the ignorance of these people who go to learn jihad there, or to learn the methods of jihad.
The second thing—apparently—and Allah knows best—is that the Amirs there have not, likewise, imposed a system on the mujahideen there that obligates them to stay there, unless they are told: You are able to be absent for a month or two or the like. In this case, it is permissible for the mujahid to leave. But I do not know if the commanders themselves have adhered to this system and imposed on all the mujahideen that they remain there as long as the public interest requires. If they permit them to leave, do they permit it? Therefore, there must be a system that obligates every mujahid, before he comes, to know that he has no return to his country except with the permission of his ruler or his authority.
This is the answer to this last question.