The first part of verse 16:90 says:
"Allah enjoins justice, generosity and kind treatment with kindred."
The verse 16:90 is being recited in Jumuah khutbas every Friday in millions of Masajid throughout the world since the time of Umar bin Abdul Aziz (may Allah T'ala be please with him).
The first of these three commandments of Allah T'ala is justice which has two aspects.
To make such arrangements as may enable everyone to get one's due rights without stint. Justice does not, however, mean equal distribution of rights, for that would be absolutely unnatural. In fact, justice means equitable dispensation of rights which in certain cases may mean equality. For example, aII citizens should have equal rights of citizenship but in other cases equality in rights would be injustice. For instance, equality in social status and rights between parents and their children will obviously be wrong. Likewise those who render services of superior and inferior types cannot be equal in regard to wages and salaries. What AIIah enjoins is that the full rights of everyone should be honestly rendered whether those be moral, social, economic legal or political in accordance with what one justly deserves.
The second thing enjoined is "ihsan" which has no equivalent in English. This means to be good, generous, sympathetic, tolerant, forgiving, polite, cooperative, selfless, etc. In collective life this is even more important than justice; for justice is the foundation of a sound society but ihsan is its perfection. On the one hand, justice protects society from bitterness and violation of rights: on the other, ihsan makes it sweet and joyful and worth living. It is obvious that no society can flourish if every individual insists on exacting his pound of flesh. At best such a society might be free from conflict but there cannot be love, gratitude, generosity, sacrifice, sincerity, sympathy and such humane qualities as produce sweetness in life and develop high values.
The third thing which has been enjoined is good treatment towards one's relatives which in fact is a specific form of ihsan. It means that one should not only treat one's relatives well, share their sorrows and pleasures and help them within lawful limits but should also share one's wealth with them according to one's means and the need of each relative. This enjoins on everyone who possesses ample means to acknowledge the share of one's deserving relatives along with the rights of one's own person and family. The Divine Law holds every well-to-do person in a family to be responsible for fulfilling the needs of aII his needy kith and kin. The Law considers it a great evil that one person should enjoy the pleasures of life while his own kith and kin are starving. As it considers the family to be an important part of society, it lays down that the first right of needy individuals is on its well-to-do members and then on the others. Likewise it is the first duty of the well-to-do members of the family to fulfil the needs of their own near relatives and then those of others. The Holy Prophet has emphasized this fact in many Traditions, according to which a person owes rights to his parents, his wife and children, his brothers and sisters, other relatives, etc. , in accordance with the nearness of their relationships. On the basis of this fundamental principle, Caliph Umar made it obligatory on the first cousins of an orphan to support him. In the case of another orphan he declared that if he had no first cousins he would have made it obligatory on distant cousins to support him. Just imagine the happy condition of the society every unit of which supports its every needy individual in this way-most surely that society will become high and pure economically, socially, and morally. (tafsir from Tafheemul Quran)