(6) بَاب مَعْنَى كُلِّ مَوْلُودٍ يُولَدُ عَلَى الْفِطْرَةِ وَحُكْمِ مَوْتِ أَطْفَالِ الْكُفَّارِ وَأَطْفَالِ الْمُسْلِمِينَ
Abu Huraira reported from Allah's Messenger (may peace be upom him) many ahadith and one amongst them is that he is reported to have said:
An infant is born according to his (true) nature. It is his parents Who make him a Jew, a Christian, just as a she-camel gives birth to its young ones. Do you find any deficiency in their limbs? You cut their ears (i. e. after birth). They (the Companions of the Holy Prophet) said: What is your opinion about him who dies in infancy? Thereupon Allah's Apostle (ﷺ) said: It is Allah alone Who knows best what they would be doing.
Reference: Sahih Muslim 2658 g
In-book reference: Book 46, Hadith 39
USC-MSA web (English) reference(deprecated numbering scheme): Book 33, Hadith 6428