It was narrated from Abdullah bin Ubaid bin Umair that a man said: "O Abu abdur-Rahman, why do I only see you touching these two corners?" He said: "I heard the Messenger of Allah say: “Touching them erases sins.' And I head him say: “whoever circumambulates seven times, it is like freeing a slave””"
SahihSahihIsnaad HasanBook 24 · Hadith 302