—and of the angels and of all people.
The second clause states that the Muslims share a single pledge of security; their covenant is one. Thus, if any Muslim who possesses the authority to grant such pledges makes a treaty with someone and another person violates that treaty, upon the violator be the curse of Allah, the angels, and all people.
For example, if a non-Muslim enters the land under a guarantee and safe-conduct from those empowered to give such guarantees—or from any Muslim who may rightly confer safety—and someone then breaks that pledge, he deserves the curse of Allah, the angels, and all people.
Suppose a disbeliever comes with a pledge of safety and an ordinary believer shelters him, saying, “Enter; you are under my protection and within my neighbourhood.” If someone subsequently kills that disbeliever, declaring, “He is an unbeliever, we must kill him,” despite the security granted by the Muslim, upon that killer be the curse of Allah, the angels, and all people. We ask Allah for well-being.
How much worse, then, when the person has entered under the explicit guarantee of the ruler, entrusted to the protection of the state, and yet someone still kills him; upon such a murderer be the curse of Allah, the angels, and all people.
This shows that Islam safeguards anyone who enters under its guarantee and hospitality, and that the religion of Islam does not countenance treachery, assassination, or criminality. Islam is a transparent faith, containing nothing but frankness. When Muslims grant a person safety, that person must indeed be safe; the whole point of the pledge is that he genuinely enjoy security.
From this we understand the error of those who break covenants, betray trusts, and assassinate people who possess a pact and guarantee of safety. Such individuals fully deserve what the Commander of the Believers, ʿAlī (may Allah be pleased with him), pronounced: upon them be the curse of Allah, the angels, and all people. We seek refuge in Allah.
Yes: as for an enemy combatant who enters without any guarantee, no Muslim having granted him safety.