The books say (E.g., DhA.i.117) that Anuruddha became an arahant after listening to this sutta. There is no sutta of this name, but the reference is evidently to the Anuruddha Sutta (A.iv.227ff), which the Buddha preached to Anuruddha who was then dwelling among the Cetis in Pácínavamsamigadáya.
Anuruddha was meditating on the seven purisa-vitakká, and the Buddha appeared before him and taught him the eighth - that the Dhamma is for the precise and for one who delights in exactness, not for the diffuse or for him who delights in diffuseness. The Buddha later addresses the monks of Sumsumáragiri and tells them of the eight mahá-purisa-vitakká.