Sahl b. Sa'd reported that Mundhir b. Aba Usaid was brought to Messenger of Allah ﷺ at the time of his birth Allah's. Apostle ﷺ placed him on his thigh and Abfi Usaid kept sitting there. Allah's Apostle ﷺ had been occupied with something else before him. Abu Usaid commanded his child to be lifted from the lap of Messenger of Allah ﷺ and so he was lifted. When Messenger of Allah ﷺ had finished the work he said: Where is the child? Abd Usaid said: Allah's Messenger, we took him away. He said: What is his name? He said;
Allah's Messenger, it is so and so, whereupon he (the Holy Prophet) said: Nay, his name is Mundhir, and named him Mundhir on that day.

حَدَّثَنِي مُحَمَّدُ بْنُ سَهْلٍ التَّمِيمِيُّ، وَأَبُو بَكْرِ بْنُ إِسْحَاقَ قَالاَ حَدَّثَنَا ابْنُ أَبِي مَرْيَمَ، حَدَّثَنَا مُحَمَّدٌ، - وَهُوَ ابْنُ مُطَرِّفٍ أَبُو غَسَّانَ - حَدَّثَنِي أَبُو حَازِمٍ، عَنْ سَهْلِ بْنِ سَعْدٍ، قَالَ أُتِيَ بِالْمُنْذِرِ بْنِ أَبِي أُسَيْدٍ إِلَى رَسُولِ اللَّهِ ﷺ حِينَ وُلِدَ فَوَضَعَهُ النَّبِيُّ ﷺ عَلَى فَخِذِهِ وَأَبُو أُسَيْدٍ جَالِسٌ فَلَهِيَ النَّبِيُّ ﷺ بِشَىْءٍ بَيْنَ يَدَيْهِ فَأَمَرَ أَبُو أُسَيْدٍ بِابْنِهِ فَاحْتُمِلَ مِنْ عَلَى فَخِذِ رَسُولِ اللَّهِ ﷺ فَأَقْلَبُوهُ فَاسْتَفَاقَ رَسُولُ اللَّهِ ﷺ فَقَالَ " أَيْنَ الصَّبِيُّ " . فَقَالَ أَبُو أُسَيْدٍ أَقْلَبْنَاهُ يَا رَسُولَ اللَّهِ . فَقَالَ " مَا اسْمُهُ " . قَالَ فُلاَنٌ يَا رَسُولَ اللَّهِ . قَالَ " لاَ وَلَكِنِ اسْمُهُ الْمُنْذِرُ " . فَسَمَّاهُ يَوْمَئِذٍ الْمُنْذِرَ .