‘Ali said

We wrote down nothing on the authority of Allah's Messenger ﷺ but the Qur’an and what this document contains. He reported Allah's Messenger ﷺ as saying, “Medina is sacred from ‘Air to Thaur, ( This phrase has been much discussed. ‘Air is known as a hill at Medina and Thaur at Mecca. Because of the difficulty some have suggested that Uhud should be read instead of Thaur, but others feel that that is unjustifiable.) so if anyone produces an innovation in it, or gives protection to an innovator, the curse of Allah, the angels, and all men will rest upon him, and no repentance or ransom (Lane in his Lexicon gives a variety of meanings for this phrase, la yuqbal minhu sarf wald 'adl. The one used above seems the most suitable here) will be accepted from him. The protection granted by Muslims is one and must be respected by the humblest of them, so if anyone breaks a covenant made by a Muslim the curse of Allah, the angels, and all men will rest upon him and no repentance or ransom will be accepted from him. If anyone gives the rights of inheritance to people without the permission of his masters, (This is explained in relation to a slave who has been set free, for the rights of inheritance still belong to his master who set him free. Cf. Book 12, ch. 6, third tradition) the curse of Allah, the angels, and all men will rest upon him, and no repentance or ransom will be accepted from him.’’ Bukhari and Muslim. A version given by both of them says, “ If anyone makes a false claim to paternity or to being a client, the curse of Allah, the angels and all men will rest upon him, and no repentance or ransom will be accepted from him.”