In the Holy Qur'an

And serve God and do not associate anything with Him and be good to the parents and to the near of kin and the orphans and the needy and the neighbour of (your) kin and the alien neighbour, and the companion in a journey and the wayfarer and those whom your right hands possess; surely Allah does not love him who is proud, boastful. (4:36)

In the Traditions

Let it be known to you, Maalik, that I am sending you as a governor to a country which has seen many regimes before this. Some of them were benign, sympathetic and good, while others were tyrannical, oppressive and cruel. People will judge your regime as critically as you have studies the activities of other regimes and they will criticize you in the same way as you have censured or approved other rulers.

Maalik! You must create in your mind kindness, compassion and love for your subjects. Do not behave towards them as if you are a voracious and ravenous beast and as if your success lies in devouring them.

Remember, Maalik, that amongst your subjects there are two kinds of people: those who have the same religion as you have; they are brothers to you, and those who religions other than that of yours, they are human beings like you.

Men of either category suffer from the same weaknesses and disabilities that human beings are inclined to, they commit sins, indulge in vices either intentionally or foolishly and unintentionally without realising the enormity of their deeds.
Let your mercy and compassion come to their rescue and help in the same way and to the same extent that you expect Allah to show mercy and forgiveness to you.

Excerpt of letter by Imam Ali to Maalik al-Astar