Sahih Bukhari Volume 1, Book 3, Hadith 101

حَدَّثَنَا آدَمُ، قَالَ حَدَّثَنَا شُعْبَةُ، قَالَ حَدَّثَنِي ابْنُ الأَصْبَهَانِيِّ، قَالَ سَمِعْتُ أَبَا صَالِحٍ، ذَكْوَانَ يُحَدِّثُ عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ،‏.‏ قَالَتِ النِّسَاءُ لِلنَّبِيِّ صلى الله عليه وسلم غَلَبَنَا عَلَيْكَ الرِّجَالُ، فَاجْعَلْ لَنَا يَوْمًا مِنْ نَفْسِكَ‏.‏ فَوَعَدَهُنَّ يَوْمًا لَقِيَهُنَّ فِيهِ، فَوَعَظَهُنَّ وَأَمَرَهُنَّ، فَكَانَ فِيمَا قَالَ لَهُنَّ ‏"‏ مَا مِنْكُنَّ امْرَأَةٌ تُقَدِّمُ ثَلاَثَةً مِنْ وَلَدِهَا إِلاَّ كَانَ لَهَا حِجَابًا مِنَ النَّارِ ‏"‏‏.‏ فَقَالَتِ امْرَأَةٌ وَاثْنَيْنِ فَقَالَ ‏"‏ وَاثْنَيْنِ ‏"

Narrated By Abu Said Al-Khudri : Some women requested the Prophet to fix a day for them as the men were taking all his time. On that he promised them one day for religious lessons and commandments. Once during such a lesson the Prophet said, "A woman whose three children die will be shielded by them from the Hell fire." On that a woman asked, "If only two die?" He replied, "Even two (will shield her from the Hell-fire)."