Sahih al-Bukhari 3734
Narrated `Abdullah bin Dinar:
One day Ibn `Umar, while in the Mosque, looked at a man who was dragging his clothes while 
walking in one of the corners of the Mosque He said, "See who is that. I wish he was near to me." 
Somebody then said (to Ibn `Umar), "Don't you know him, O Abu `Abdur-Rahman? He is 
Muhammad bin Usama." On that Ibn `Umar bowed his head and dug the earth with his hands and 
then, said, "If Allah's Messenger (ﷺ) saw him, he would have loved him."
حَدَّثَنِي الْحَسَنُ بْنُ مُحَمَّدٍ، حَدَّثَنَا أَبُو عَبَّادٍ، يَحْيَى بْنُ عَبَّادٍ حَدَّثَنَا الْمَاجِشُونُ، أَخْبَرَنَا عَبْدُ اللَّهِ بْنُ دِينَارٍ، قَالَ نَظَرَ ابْنُ عُمَرَ يَوْمًا وَهْوَ فِي الْمَسْجِدِ إِلَى رَجُلٍ يَسْحَبُ ثِيَابَهُ فِي نَاحِيَةٍ مِنَ الْمَسْجِدِ فَقَالَ انْظُرْ مَنْ هَذَا لَيْتَ هَذَا عِنْدِي‏.‏ قَالَ لَهُ إِنْسَانٌ أَمَا تَعْرِفُ هَذَا يَا أَبَا عَبْدِ الرَّحْمَنِ هَذَا مُحَمَّدُ بْنُ أُسَامَةَ، قَالَ فَطَأْطَأَ ابْنُ عُمَرَ رَأْسَهُ، وَنَقَرَ بِيَدَيْهِ فِي الأَرْضِ، ثُمَّ قَالَ لَوْ رَآهُ رَسُولُ اللَّهِ صلى الله عليه وسلم لأَحَبَّهُ‏.‏