Sahih Al Bukhari Hadith Number 1613

Narrated Ibn `Abbas: The Prophet (peace be upon him) performed Tawaf of the Ka`ba riding a camel, and every time he came in front of the Corner (having the Black Stone), he pointed towards it with something he had with him and said Takbir.

25  Hajj (Pilgrimage)
Hadith number 1613
Volume no 2
Chapter: 62 (To say Takbir in front of the Corner (having the Black Stone)