Shaykh Al-Fawzaan said, “Such a person giving this verdict [that it is permissible to kill non-Muslims in Muslim lands] is ignorant because this is a detailed matter.
As for someone they have a peace agreement with us and he enters our country [Saudi Arabia or any other Muslim country] legally in safety or if we [our government] have requested them to come to perform some work we need from them, then such people are under a covenant of safety from us and a peace treaty.
It is not permissible for anyone to act treacherously towards such people nor is it permissible to harm or kill them.
Any [non-Muslim] country that there exists between them and us [the Muslim nations] a peace treaty or diplomatic relations, it is forbidden to act hostile against them [non-Muslim citizens from those non-Muslim lands when they are in the Muslim lands].
Those non-Muslims who have entered our country [Saudi Arabia or any Muslim nation] legitimately with permission [by obtaining a visa], it is forbidden to harm them.
Allah says, “And if anyone of the polytheists (disbelievers, non-Muslims, etc.) seeks your protection, then grant him protection, so that he may hear the word of Allah (the Quran), and then escort him to his place of safety and security.” [Surah al-Tawbah, 9:6]
So, it is not allowed to harm or act treacherously against anyone who enters any land of the Muslims legally with their permission or if the Muslims request their presence.
Such talk [that it is permissible to harm such non-Muslims in the Muslim lands] is forbidden.”
Ref: The cassette: Fatawa al-Ulama fi al-Ahdsth al-Rahinah allati Hadathat bisharq Madinah ar-Riyadh
Posted by Abdul Kareem Ibn Ozzie