Sunan an-Nasa'i, Volume 2, Book 13, Hadith 1217 (DarusSalam) ⓘ

It was narrated from Abu Salamah that : Abu Hurairah said: "The Messenger of Allah stood up to pray and we stood up with him. A Bedouin said- while he was praying- 'O Allah, have mercy on me and Muhammad and do not have mercy on anyone else.' When the Messenger of Allah said the Salam, he said to the Bedouin: 'You have limited something vast," meaning the mercy of Allah (SWT)."

أَخْبَرَنَا كَثِيرُ بْنُ عُبَيْدٍ، قَالَ حَدَّثَنَا مُحَمَّدُ بْنُ حَرْبٍ، عَنِ الزُّبَيْدِيِّ، عَنِ الزُّهْرِيِّ، عَنْ أَبِي سَلَمَةَ، أَنَّ أَبَا هُرَيْرَةَ، قَالَ قَامَ رَسُولُ اللَّهِ صلى الله عليه وسلم إِلَى الصَّلاَةِ وَقُمْنَا مَعَهُ فَقَالَ أَعْرَابِيٌّ وَهُوَ فِي الصَّلاَةِ اللَّهُمَّ ارْحَمْنِي وَمُحَمَّدًا وَلاَ تَرْحَمْ مَعَنَا أَحَدًا ‏.‏ فَلَمَّا سَلَّمَ رَسُولُ اللَّهِ صلى الله عليه وسلم قَالَ لِلأَعْرَابِيِّ ‏ "‏ لَقَدْ تَحَجَّرْتَ وَاسِعًا ‏" ‏ ‏.‏ يُرِيدُ رَحْمَةَ اللَّهِ عَزَّ وَجَلَّ ‏.‏