Nafi' reported on the authority of 'Abdullah (Allah be pleased with him) that Messenger of Allah (way peace be upon him) did not touch but the Stone and the Yamani corner. (Using translation from Muslim 1267c)
أَنَّ رَسُولَ اللهِ ﷺ كَانَ «لَا يَسْتَلِمُ إِلَّا الْحَجَرَ وَالرُّكْنَ الْيَمَانِيَّ»