عَنِ ابْنِ عَبَّاسٍ رَضِيَ اللَّهُ عَنْهُمَا كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ لَا يَسْتَلِمُ إِلَّا هَذَيْنِ الرُّكْنَيْنِ الْيَمَانِيَّ وَالْأَسْوَدَ
It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) used to perform istilam (touching or kissing) of only two corners, namely the Rukn Yamani and the Hajar Aswad.