Sadaqah (optional charity) refers to helping others in any way, by giving them in charity, by spending some time with them, listening to them attentively, directing them to the right path, feeling for them, smiling to them, removing whatever may harm them in streets, etc. All these are instances of sadaqah in its comprehensive sense.
Hidden Sadaqah is what one gives in secret with no one but Almighty Allah knowing about it. When one gives charity to a needy person in secret, one spares the needy person the feelings of inferiority he may experience if given charity in front of other people.
Hidden Sadaqah will help the needy meet their needs and will also help them get rid of the negative feelings of envy and grudge they might have harbored towards the rich people.
Feelings of love and respect would grow then between the needy and rich people, and this, in turn, would positively reflect on the unity of society and bind its members with the bonds of love and cooperation.
When the poor’s needs are met in an atmosphere that preserves them their dignity, the tension they would live in because of need will decrease and their energy for work will increase. This will reflect positively on their social relations with others.
There are many poor people who are in dire need, yet they restrain from asking for charity. Hidden Sadaqah will help them a lot and spare them exposure to humiliation.
Allah Almighty says about that kind of people: [(Alms are) for the poor who are straitened for the cause of Allah, who cannot travel in the land (for trade). The unthinking man accounteth them wealthy because of their restraint. Thou shalt know them by their mark: They do not beg of men with importunity.] (Al-Baqarah: 273)
As for he who gives hidden sadaqah, the process of giving itself provides him with great happiness and purifies his soul. It helps him get rid of selfishness and develop feelings of cooperation with others. It is also a means of protecting his wealth, [for when he gives others, he wins their love, and thus spares himself the influence of their envy.] In essence, giving sadaqah reflects on the giver and benefits him [as much as it benefits the recipients].
Allah Almighty says: [And whatsoever good thing ye spend, it is for yourselves, when ye spend not save in search of Allah's countenance; and whatsoever good thing ye spend, it will be repaid to you in full, and ye will not be wronged.] (Al-Baqarah: 272)
Furthermore, hidden sadaqah helps its givers get rid of feelings of depression that they may experience. When one gives the poor, one feels deep happiness, especially when one hears them praying for one and expressing gratitude for one.
Contemplate the image Allah Almighty gives in the following verse that describes the example of the one who gives generously in charity: [And the likeness of those who spend their wealth in search of Allah's pleasure, and for the strengthening of their souls, is as the likeness of a garden on a height. The rainstorm smiteth it and it bringeth forth its fruit twofold. And if the rainstorm smite it not, then the shower. Allah is Seer of what ye do.] (Al-Baqarah: 265)
Based on the above lines, the psychological analysis of the influence of hidden sadaqah on both the giver and the recipient shows that it extinguishes the humiliation of the recipient and the embarrassment of the giver. It creates between them such an atmosphere of peaceful coexistence that Almighty Allah is pleased with. Moreover, it extinguishes the wrath that Allah Most High may have towards the giver, for there is a divine hadith to the effect that “the hidden Sadaqah extinguishes Allah’s wrath.”