I saw'lbn 'Umar (Allah be pleased with them) touching the Stone with his hand and then kissing his hand. and he said: I have never abandoned it since I saw Messenger of Allah (way peace be upon him) doing It. (Using translation from Muslim 1268b)
وَقَالَ مَا تَرَكْتُهُ مُنْذُ رَأَيْتُ رَسُولَ اللهِ ﷺ يَفْعَلُهُ