جامع الترمذي

Narrated An-Nawwas bin Sam'an Al-Kilabi: that the Messenger of Allah (ﷺ) said: "Indeed Allah has made a parable of the straight path: At the sides of the path there are walls with open doors, each door having a curtain. There is a caller at the head of the path calling, and a caller above it calling. And Allah invites to the abode of peace and guides whomever He wills to the straight path. The doors which are on the sides of the path are the Hudud (legal limitations) of Allah; no one breaches the Hudud of Allah except that curtain is lifted, and the one calling from above it is his Lord."