“ …the evidence illustrates that Islamic orthodoxy generally condones the practice, whilst not explicitly recommending it per se. The most egregious case in point is the Umdat Al-Salik ("Reliance of the Sojourner" in Arabic), a manual on Shari'a (Islamic law) certified by Al-Azhar University, the most prominent and authoritative institute of Islamic jurisprudence in the world, as a reliable guide to orthodox Sunni Islam.
The manual states (01.1-2) that "retaliation is obligatory against anyone who kills a human being purely intentionally and without right," except when "a father or mother (or their fathers or mothers)" kills his or her "offspring, or offspring's offspring." Hence, according to this view a parent, who murders his or her son/daughter for the sake of "honor," whether owing to issues of chastity, apostasy and the like, incurs no penalty under Shari'a. This ruling is derived from a hadith (Sahih Muslim, Book 19, Number 4457) where it is affirmed that one should not kill a child unless one could know "what Khadir had known about the child he killed." Khadir is a figure featured in the Qur'an who accompanies Moses on a journey and kills a son of believing parents for fear that he would rebel against the will of God (18:74 and 18:80-81)”
