It is narrated from Sayyiduna Umar (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said to him: "Umar! You are a strong man, do not push while kissing the Black Stone, lest you cause harm to a weak person. If you find an empty space, then perform istilam; otherwise, suffice with facing it and reciting tahlil and takbir."
Hadith Referenceمسند احمد / مسند الخلفاء الراشدين / 190
Hadith Gradingحکم دارالسلام:حديث حسن، الشيخ الذى روى عنه أبو يعفور مجهول، وسماه سفيان ابن عيينة : عبدالرحمن بن نافع بن عبدالحارث، والحديث مرسل