The previous verses interpreted are about addressing an important issue: the stinginess of soul and spending in the way of Allah (swt). They have clarified all the issues related spending in the way of Allah (swt) and the hypocrisy thereof along with all the ways by which Satan can disturb a person while paying the obligatory Zakat or charities, a Sunnah of Prophet Muhammad (saws). Then, Allah (swt) continues the talk about spending:
(… وَمَا أَنفَقْتُم مِّن نَّفَقَةٍ أَوْ نَذَرْتُم مِّن نَّذْرٍ ) (And whatever you spend of expenditures or make of vows …): We’ve talked much about expenditure. Yet, it’s the first time we have the word ‘vows’ mentioned. What does it mean here? It means that one does something of the same nature as what the Almighty has enjoined upon them beyond what’s been obligated. For example, the Almighty has enjoined five time prayers upon us, and we may perform the Sunnah prayers. Yet, someone may vow to pray forty Rakaa’s voluntarily for Allah. This is of the same nature of what Allah has enjoined upon us i.e. the prayers but beyond what has been obligated (the five-time prayers) by the Almighty. Another example is that someone may vow to slaughter a goat or a sheep…etc. which is similar to slaughter done in Al-Adha Eid, but you rather do that at a different time in this case. So, a vow should be about something of the same nature of what the Almighty has ordered and mustn’t be contradictory to it.
(… فَإِنَّ اللَّهَ يَعْلَمُهُ …) (…Allah knows of it …): The conclusion of this verse indicates that Allah (swt) knows the sincerity and honesty of one’s intention. Plus, we all know that half of the religion has been stated in one Hadith in Sahih al-Bukhari, narrated by Omar Bin Al-Khattab (may Allah be pleased with him) that the Messenger of Allah (saws) said:
“The value of an action depends on the intention behind it. So every work relates to the sincerity of the intention.”
Thus, it’s all about the sincerity of the intention. Allah (swt) knows everything when you spend or make a vow. As long as any action is done with a sincere intention, it will be rewarded accordingly by the Almighty, whereas, if such action is done for the sake of hypocrisy or worldly interest, then Allah (swt) is so self-sufficient, and the action won’t be rewarded in this case. A reward is only taken from whom one work for.
( وَمَا لِلظَّالِمِينَ مِنْ أَنصَارٍ … ) (…And for the wrongdoers there are no helpers): What’s the relevance of ‘wrongdoing’ here? There are different types of wrongdoing, the severest of which is to do the wrong to one’s self not others. Moreover, wrongdoing has two types: the first is when one does wrong to themselves by giving priority to trivial desire over an everlasting paradise, the mundane over the heavenly, and what people have over what the Lord of humans. The second one is to do wrong to others. So, (And for the wrongdoers there are no helpers.) means that they will be helped neither in this life nor in the afterlife since they have their deeds for the sake of humans rather than the Lord.
 Hadith no. 1, How the Divine Revelation started being revealed to Allah’s Messenger, Revelation Vol, Sahih al-Bukhari.