Any Muslim who loses three of his children will not be touched by the Fire except in fulfillment of the oath
Authentic hadithعن أبي هريرة رضي الله عنه قال: قال رسول الله صلى الله عليه وسلم : «لا يَمُوتُ لأحَدٍ من المسلمين ثلاثة من الوَلَد فتَمسُّه النَّار إلا تَحِلَّة القَسَم».
Abu Hurayrah (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: "Any Muslim who loses three of his children will not be touched by the Fire except in fulfillment of the oath."
Explanation
Whoever loses three children, whether they were male or female, then Allah will prohibit the fire of Hell from burning him, on condition that he was patient and content with Allah’s divine will. However, Allah will subject him to what He promised in the Qur'an, which is crossing over the Sirāt, or the bridge that passes over the Hellfire, in the verse: {There is not one of you but will pass over it (Hell); this is with your Lord a Decree which must be accomplished.} [Sūrat Maryam: 71]
Source · Narrated by Bukhari & Muslim
From the Hadith Encyclopedia (hadeethenc.com).