أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا حَمَّادٌ، عَنِ الزُّبَيْرِ بْنِ عَرَبِيٍّ، قَالَ سَأَلَ رَجُلٌ ابْنَ عُمَرَ عَنِ اسْتِلاَمِ الْحَجَرِ، فَقَالَ رَأَيْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَسْتَلِمُهُ وَيُقَبِّلُهُ ‏.‏ فَقَالَ الرَّجُلُ أَرَأَيْتَ إِنْ زُحِمْتُ عَلَيْهِ أَوْ غُلِبْتُ عَلَيْهِ فَقَالَ ابْنُ عُمَرَ رضى الله عنهما اجْعَلْ أَرَأَيْتَ بِالْيَمَنِ رَأَيْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَسْتَلِمُهُ وَيُقَبِّلُهُ ‏.‏

It was narrated that Az-Zubair bin Adiyy said: "A man asked Ibn Umar about touching the Black Stone and he said: 'I saw the Messenger of Allah touching it and kissing it.' The man said: 'What if it is too crowded and I am overwhelmed?' Ibn Umar, may Allah be pleased with him, said: 'Leave your "what if" in Yemen! I saw the Messenger of Allah touching it and kissing it.'" Translation Not Available

Book Ref: Sunan An Nisai Book 24 Hadith 2946
Web Ref:  Sunan An Nisai Vol 3 Book 24 Hadith 2949