"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 'Abdullah bin 'Umar : The Jew brought to the Prophet a man and a woman from amongst them who have committed (adultery) illegal sexual intercourse. He ordered both of them to be stoned (to death), near the place of offering the funeral prayers beside the mosque." - Sahih Bukhari 7:62:64 (read more)

"Circumcision [of females] is not an inherited custom as some people claim, rather it is prescribed in Islam and the scholars are unanimously agreed that it is prescribed. Not a single Muslim scholar – as far as we know – has said that circumcision is not prescribed. Their evidence is to be found in the saheeh ahaadeeth of the Prophet (peace and blessings of Allaah be upon him), which prove that it is prescribed... Thus it is clear that the fuqaha’ of Islam are agreed that circumcision is prescribed for both males and females, and in fact the majority of them are of the view that it is obligatory for both. No one said that it is not prescribed or that it is makrooh or haraam." - Islam Q&A