Sunan an-Nasa'i, Volume 3, Book 24, Hadith 2949 (DarusSalam) ⓘ

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.'"

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 ‏.‏