Allah has undertaken to provide for one who leaves his home (only) to fight for His cause and to affirm the truth of His word; Allah will either admit him to Paradise or will bring him back home from where he had come out, with his reward and booty.

"Allah, the Mighty and Sublime, has guaranteed to the one who strives in His cause, only going out for Jihad in His cause, and believing in His Word, that He will admit him to Paradise, or bring him back to his home from which he emerged, with whatever he has earned of reward, or spoils of war."

(The value of) an action depends on the intention behind it. A man will be rewarded only for what he intended. The emigration of one who emigrates for the sake of Allah and His Messenger (ﷺ) is for the sake of Allah and His Messenger (ﷺ) ; and the emigration of one who emigrates for gaining a worldly advantage or for marrying a woman is for what he has emigrated.

Allah's Messenger (ﷺ) said, "Allah guarantees him who strives in His Cause and whose motivation for going out is nothing but Jihad in His Cause and belief in His Word, that He will admit him into Paradise (if martyred) or bring him back to his dwelling place, whence he has come out, with what he gains of reward and booty."

I heard Allah's Messenger (ﷺ) saying, "The (reward of) deeds, depend upon the intentions and every person will get the reward according to what he has intended. So whoever emigrated for the sake of Allah and His Apostle, then his emigration will be considered to be for Allah and His Apostle, and whoever emigrated for the sake of worldly gain or for a woman to marry, then his emigration will be considered to be for what he emigrated for."