عَنِ ابْنِ عُمَرَ رَضِيَ اللَّهُ عَنْهُمَا أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ كَانَ يَأْتِي الْبَيْتَ فَيَسْتَلِمُ الْحَجَرَ وَيَقُولُ: ((بِسْمِ اللَّهِ وَاللَّهُ أَكْبَرُ))
It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that when the Messenger of Allah (peace and blessings be upon him) would enter the House of Allah and touch the Black Stone, he would recite these words: Bismillah, Allahu Akbar.