Any Muslim who loses (to death) three children before reaching puberty will be admitted by Allah into Paradise because of his being merciful to them.
[Al-Bukhari]
Original Hadith
"«ما مِنْ مُسْلِم يموت له ثلاثة لم يَبْلُغوا الحِنْثَ إلا أدْخَلَه الله الجنَّة بِفَضْل رَحْمَتِهِ إيَّاهُمْ».
[صحيح.] - [رواه البخاري.]"