Allah has guaranteed for the one who fights in His cause to admit him into Paradise if He takes his soul, or to return him safe and sound with reward or booty.

In this Hadīth, there is a guarantee from Allah for the one who leaves in His cause and for whom nothing other than Jihad is the reason for his leaving, as a sincere believer, that he has a promise from Allah for one of three things or two. If he is killed, then he will have a guarantee from Allah to admit him into Paradise, and if he remains alive, then Allah will return him home with any reward and war booty he obtained, meaning: reward without war booty or both.
As for the second narration, which was attributed by the author of Al-‘Umdah to Muslim, and which is agreed upon, it states that the virtue of Jihad in the cause of Allah, meaning: what is like Jihad but exceeds the human ability is that, instead of going out in the way of Allah, one enters one's place of prayer and continuously prays and fasts, and this is why the Prophet (may Allah's peace and blessings be upon him) said: "You will not be able to do so."