Sunan At-Tirmidhi

Nafi' narrated that a man came to Ibn 'Umar and said:""So-and-so conveys his Salam to you."" So he said: ""It has been conveyed to me that he has innovated, so if he has indeed innovated, then do not convey my Salam to him, for I heard the Messenger of Allah (s.a.w) saying: 'In this Ummah' or: 'In my Ummah'"" - the doubt was his - ""a collapse of the earth, or a transformation, or stones shall rain upon the people of Al-Qadr