Hadith no. 2367 (below) is a repeat. Read it here.
Volume 3, Book 49, Number 869 :
Narrated by Abdullah bin Kab bin Malik from Kab bin Malik (radiallaahu `anhu)
Abdullah bin Abu Hadrad Al-Aslami owed Kab bin Malik (radiallaahu `anhu) some money. One day the latter met the former and demanded his right, and their voices grew very loud. The Prophet (sallallaahu `alayhi wasallam) passed by them and said, “O Ka’b,” beckoning with his hand as if intending to say, “Deduct half the debts.” So, Ka’b (radiallaahu `anhu) took half what the other owed him and remitted the other half.
Volume 3, Book 49, Number 870 :
Narrated by Abu Huraira (radiallaahu `anhu)
Allah’s Apostle (sallallaahu `alayhi wasallam) said, “There is a Sadaqa to be given for every joint of the human body; and for every day on which the sun rises there is a reward of a Sadaqa (i.e. charitable gift) for the one who establishes justice among people.”
The daily sadaqah due on human body is like an act of gratitude. Something we do to show thankfulness to Allah for our health and physical wellness etc. One can do so by doing acts of worship like prayer, charity and fasting etc., because what is worship if not gratitude?
In a normal give-and-take deal, the matter would end with us completing our side of the bargain: You give me something, I pay back, the end. But when it comes to dealing with Allah, it’s not like this at all. He gives us blessings (of health, wealth, family etc.), we show gratefulness (and so little of it!) by praying, fasting, giving in charity etc. And it doesn’t end there, He rewards us for our worship and gratitude. But we don’t do anything for Him in return. You see, with Allah, we always have the lower hand. We’re always taking something, benefiting, while He keeps giving and giving without measure. You’ve got to be utterly stupid to complain!
Establishing justice among people is not for qualified judges only. Everyone can do it in their own capacity. If you’re a parent, treat your children fairly; teacher, no favoritism; leader, solve matters honestly, and so on. Any decision you take regarding your attitude towards people has an element of justice in it. If you do it right, you’re rewarded. Is Allah not generous?