Ayat 121. Nor do they spend anything (in Allah's Cause) - small or great - nor cross a valley, but is written to their credit, that Allah may recompense them with the best of what they used to do (i.e. Allah will reward their good deeds according to the reward of their best deeds which they did in the most perfect manner).
Ayat 122. And it is not (proper) for the believers to go out to fight (Jihad) all together. Of every troop of them, a party only should go forth, that they (who are left behind) may get instructions in (Islamic) religion, and that they may warn their people when they return to them, so that they may beware (of evil).
Hazrat Abu Umamah (May Allah be pleased with him) reported: The Messenger of Allah [SAWW](PBUH) said, "The best of charities is to provide canopy in the Cause of Allah, to pay wages to a servant in the way of Allah, and to provide a camel in the way of Allah (to be used by a Mujahid).'' [At-Tirmidhi Hadith # 1627].
Lesson : as mentioned above in Surah At-Taubah Ayat 121. "do they spend anything (in Allah's Cause) small or great." Here, the word canopy (tent) stands for a covered canopy tent which can provide a Mujahid with shade for peace and comfort, and "pay wages'' means to provide a servant who can help and serve him. "Fahl'' literally means camel and "Taruqah'' is that young she-camel which can bear offspring, that is a young healthy she-camel which can be of service to the Mujahid. What all this means is that such work is highly meritorious which can provide a Mujahid with comfort, power and food. Allah holds promise of a rich reward for it.