The Prophet (ﷺ) said, "A Muslim whose three children die before the age of puberty will be granted Paradise by Allah due to his mercy for them."
Sahih al-Bukhari Book 23, Hadith 11
← Previous Hadith A person died and Allah's Messenger (ﷺ) used to visit him. He died at night and (the people) buried him at night. In the morning they informed the Prophet (about his death). He said, "What prevented you from informing me?" They replied, "It was night and it was a dark night and so we disliked to trouble you." The Prophet (ﷺ) went to his grave and offered the (funeral) prayer.

Sahih al-Bukhari Book 23, Hadith 10 Next Hadith → The women requested the Prophet, "Please fix a day for us." So the Prophet (ﷺ) preached to them and said, "A woman whose three children died would be screened from the Hell Fire by them," Hearing that, a woman asked, "If two died?" The Prophet (ﷺ) replied, "Even two (would screen her from the (Hell) Fire. " And Abu Huraira added, "Those children should be below the age of puberty. "

Sahih al-Bukhari Book 23, Hadith 12