Abu Hurairah (May Allah be pleased with him) reported:
The Messenger of Allah (ﷺ) said, "A Muslim whose three children die (in infancy) will not be touched by the Fire (of Hell) except for the fulfillment of Allah's Oath."[Al-Bukhari and Muslim].[Allah's Oath here refers to His Ayah: "There is not one of you but will cross over it (Hell)." (19:71) And the crossing will be across the 'Bridge' set over the Hell.]
App reference: Book 7, Hadith 59
Arabic/English book reference: Book 7, Hadith 953