Explanation
These several reports were gathered by Imām al-Nawawī—may Allah have mercy on him—in Riyāḍ al-Ṣāliḥīn, in the Book of Jihād. They yield a number of rulings and lessons:

1. The Prophet ﷺ showed excellent management of his Companions’ affairs. A man once came to him and said, “I want to set out for battle, but I have nothing with which to equip myself.” The Prophet ﷺ directed him to another Companion who had already prepared for the campaign but had fallen ill. The would-be fighter went to that man, took his gear, and the owner said to his wife, “Do not hold anything back from it; if you leave nothing, Allah will bless what remains for us.” Thus he equipped him completely.
2. These narrations prove that whoever outfits a combatant and supplies him with what he needs receives the same reward as the one who actually fights, and that whoever looks after the combatant’s family shares his reward as well. The incident of Banū Lihyān corroborates this: the Prophet ﷺ instructed them that one man should go forth while another stays behind to tend the fighter’s family; the one who stays behind receives half the reward, with the other half belonging to the combatant himself.
3. Among the virtues of jihād mentioned here is the saying that “the gates of Paradise are under the shade of swords,” meaning that engaging in combat becomes a cause for entering Paradise through its gates. It is authentically reported that in Paradise there is a gate called the Gate of Jihād, through which those who fought in Allah’s cause will enter.
4. These hadiths also teach that martyrdom wipes out every sin except debt—that is, a debt owed to another person. Martyrdom does not erase such a liability, because the rights of human beings must be fulfilled either in this world or in the Hereafter. The narration therefore warns against treating debt lightly.