A man asked Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) about touching the Black Stone. He said: "The Prophet (peace and blessings be upon him) used to touch it and kiss it." The man said: "What do you think if there is a crowd and I am overpowered?" He said: "Leave this 'what do you think' in Yemen. I saw the Prophet (peace and blessings be upon him) touching it and kissing it."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9222