Sunan an-Nasa'i 2955
It was narrated from Abdullah bin Abbas that:
the Messenger of Allah used to circumambulate the House on his mount, and when he reached the Corner be pointed to it." (Sahih) 
Chpater 161. They Saying Of Allah, The Mighty And Sublimse: "Take Your Adornment To Every Masjid"
أَخْبَرَنَا بِشْرُ بْنُ هِلاَلٍ، قَالَ أَنْبَأَنَا عَبْدُ الْوَارِثِ، عَنْ خَالِدٍ، عَنْ عِكْرِمَةَ، عَنْ عَبْدِ اللَّهِ بْنِ عَبَّاسٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ يَطُوفُ بِالْبَيْتِ عَلَى رَاحِلَتِهِ فَإِذَا انْتَهَى إِلَى الرُّكْنِ أَشَارَ إِلَيْهِ ‏.‏