Sheikh Mohammed Ahmed Hussein, the Grand Mufti of Jerusalem and the Palestinian territories, said again on Tuesday that it is forbidden to allow any part of Jerusalem and the land of Palestine to be sold to the "occupiers"
The fatwa says, "Praise be to Allah, Lord of the Worlds, and prayers and peace be upon the honorable prophets and messengers, our master Muhammad, may Allah bless him and his family and companions,
"It is considered a betrayal of Allah, His Messenger, peace be upon him, and the faithfulness of Islam (Al-Anfal: 27), for the sinner who sells his land to his enemies, or takes compensation for it; because the seller of the land to the enemies results in the removal of Muslims from their homes....the sale of land to the enemies and brokering them to [middlemen?] is essentially blasphemy, and is considered loyalty to the infidels and warriors, and one whose loyalty is away from Islam is a traitor to Allah, His Messenger, peace be upon him, his religion, and his homeland.
"The Muslims must boycott him. They do not treat him or marry him, nor do they seek him, do not attend his funeral, do not pray with him or bury him in Muslim graves."
This is essentially a demand for excommunication. But excommunication in Islam is controversial even against unbelievers, as Wikipedia summarizes:
Takfir or takfeer (Arabic: تكفير takfīr) is a controversial concept in Islamist discourse, denoting excommunication, as one Muslim declaring another Muslim as a non-believer (kafir). The act which precipitates takfir is termed mukaffir. Contemporary formulation and usage of the term have its roots in the 20th-century Islamist theorist Sayyid Qutb's advocacy of takfirism (doctrine of excommunication) against the state or society which deemed as jahiliyah (state of ignorance and disbelief). According to Qutb, violence is required to be sanctioned against corrupt state leaders, on the premise that quietism is not the Islamic prescriptions against one who deemed as apostates. This position is widely held and applied by jihadist organizations to varying degrees. At the same time, the concept is opposed by religious establishment as an ostensible reason for violence. They hold that excommunication against those who profess their Islamic faith is not sanctioned by Islam, or an ill-founded takfir accusation is a major forbidden act (haram).So nowadays, the only people who try to apply this idea of excommunication are jihadists (and Iran, which did it to Salman Rushdie.) Mainstream Islam says very explicitly that if a person declares himself to be a believer, he is believed - only people who admit to be apostates can be considered to be unbelievers.
Yet the current Palestinian Grand Mufti is issuing a fatwa that places the sale of land to Jews in the same category as the worst possible crime in Islam, with a punishment that goes beyond Islamic law. He is saying that selling land is blasphemy, which has no legal basis whatsoever. (He did use a Quranic verse, 60:9, that says that those who drive Muslims out of their homes are wrongdoers, and he equates the sellers of land to the people who drive people out of their homes, but even then the Quran never says they are blasphemers.)
Mainstream Muslim clerics should be as adamant against this fatwa as they are against ISIS, since Qutb's idea of takfirism is based on a relatively new interpretation of the Quran - and the mufti Hussein is going way beyond Qutb in declaring that selling land is legally the same as blasphemy and treachery.
Apparently, perverting Islamic law is OK if it serves a valuable political purpose.