"Until, when he reached the setting of the sun, he found it set in a spring of murky water: Near it he found a People: We said: “O Zul-qarnain! (thou hast authority,) either to punish them, or to treat them with kindness." - Quran 18:86 (read more)

"Narrated Kurib: the freed slave of Ibn 'Abbas, that Maimuna bint Al-Harith told him that she manumitted a slave-girl without taking the permission of the Prophet. On the day when it was her turn to be with the Prophet, she said, "Do you know, O Allah's Apostle, that I have manumitted my slave-girl?" He said, "Have you really?" She replied in the affirmative. He said, "You would have got more reward if you had given her (i.e. the slave-girl) to one of your maternal uncles." - Sahih Bukhari 3:47:765 (read more)

"It is not permissible to give zakaah on one’s wealth or crops, or Zakaat al-Fitr, to kaafirs, even if they are poor, or wayfarers, or debtors, and if one who gives zakaah to them, that is not counted as zakaah ... It is permissible to give zakaah funds to those kaafirs who hold positions of authority and influence among their people, if there is the hope that by giving them something they may become Muslims, then those who are under them may become Muslim too." - Sheikh Muhammed Salih Al-Munajjid