I saw Umar look at the Black Stone and say, "By Allah, had I not seen the Messenger of Allah ﷺ kiss you, I would not kiss you." Then he kissed it.
حدثنا أسود بن عامر قال حدثنا زهير عن سليمان الأعمش حدثنا إبراهيم
رأيت عمر نظر إلى الحجر فقال أما والله لولا أني رأيت رسول الله ﷺ يقبلك ما قبلتك ثم قبله
Its isnad is sahih. Zuhayr is Ibn Muawiya. Ibrahim is Ibn Yazid Nakhai. Aabis bin Rabia is Nakhai al-Kufi, and he is a trustworthy mukhadram successor. The hadith has many routes of transmission, and it was narrated by the authors of the six books. See al-Muntaqa 2536.