It was narrated from ‘Abdullah that the Messenger of Allah ﷺ said:
“Whoever sends fourth three of his children who had not reached the age of puberty, they will be a strong fortification for him against the Fire.” Abu Dharr said: “I sent forth two.” He said: “And two” Ubayy bin Ka’b, the chief of the reciters, said: “I sent forth one.” He said: “Even one.”

حَدَّثَنَا نَصْرُ بْنُ عَلِيٍّ الْجَهْضَمِيُّ، حَدَّثَنَا إِسْحَاقُ بْنُ يُوسُفَ، عَنِ الْعَوَّامِ بْنِ حَوْشَبٍ، عَنْ أَبِي مُحَمَّدٍ، مَوْلَى عُمَرَ بْنِ الْخَطَّابِ عَنْ أَبِي عُبَيْدَةَ، عَنْ عَبْدِ اللَّهِ، قَالَ قَالَ رَسُولُ اللَّهِ ﷺ " مَنْ قَدَّمَ ثَلاَثَةً مِنَ الْوَلَدِ لَمْ يَبْلُغُوا الْحِنْثَ كَانُوا لَهُ حِصْنًا حَصِينًا مِنَ النَّارِ " . فَقَالَ أَبُو ذَرٍّ قَدَّمْتُ اثْنَيْنِ . قَالَ " وَاثْنَيْنِ " . فَقَالَ أُبَىُّ بْنُ كَعْبٍ أَبُو الْمُنْذِرِ سَيِّدُ الْقُرَّاءِ قَدَّمْتُ وَاحِدًا . قَالَ " وَوَاحِدًا " .