Sahih Bukhari Volume 8, Book 78, Hadith 6193

حَدَّثَنَا سَعِيدُ بْنُ أَبِي مَرْيَمَ، حَدَّثَنَا أَبُو غَسَّانَ، قَالَ حَدَّثَنِي أَبُو حَازِمٍ، عَنْ سَهْلٍ، قَالَ أُتِيَ بِالْمُنْذِرِ بْنِ أَبِي أُسَيْدٍ إِلَى النَّبِيِّ صلى الله عليه وسلم حِينَ وُلِدَ، فَوَضَعَهُ عَلَى فَخِذِهِ وَأَبُو أُسَيْدٍ جَالِسٌ، فَلَهَا النَّبِيُّ صلى الله عليه وسلم بِشَىْءٍ بَيْنَ يَدَيْهِ، فَأَمَرَ أَبُو أُسَيْدٍ بِابْنِهِ فَاحْتُمِلَ مِنْ فَخِذِ النَّبِيِّ صلى الله عليه وسلم فَاسْتَفَاقَ النَّبِيُّ صلى الله عليه وسلم فَقَالَ ‏"‏ أَيْنَ الصَّبِيُّ ‏"‏‏.‏ فَقَالَ أَبُو أُسَيْدٍ قَلَبْنَاهُ يَا رَسُولَ اللَّهِ‏.‏ قَالَ ‏"‏ مَا اسْمُهُ ‏"‏‏.‏ قَالَ فُلاَنٌ‏.‏ قَالَ ‏"‏ وَلَكِنْ أَسْمِهِ الْمُنْذِرَ ‏"‏‏.‏ فَسَمَّاهُ يَوْمَئِذٍ الْمُنْذِرَ‏.‏

Narrated By Sahl : When Al-Mundhir bin Abu Usaid was born, he was brought to the Prophet who placed him on his thigh. While Abu Usaid was sitting there, the Prophet was busy with something in his hands so Abu Usaid told someone to take his son from the thigh of the Prophet. When the Prophet finished his job (with which he was busy), he said, "Where is the boy?" Abu Usaid replied, "We have sent him home." The Prophet said, "What is his name?" Abu Usaid said, "(His name is) so-and-so. " The Prophet said, "No, his name is Al-Mundhir." So he called him Al-Mundhir from that day.