It wasnarrated from 'Abdullah that the Messenger of Allah (ﷺ)said:
"Whoever sends fourth three of his children who had not reachedtheage of puberty, they will be a strong fortification for himagainstthe Fire." Abu Dharr said: "I sent forth two." He said: "Andtwo" Ubayy bin Ka'b, the chief of the reciters, said: "I sentforthone." He said: "Even one." (IT)
English reference (IT): Vol. 1, Book 6, Hadith 1606 (IT)
Arabic reference (IT): Book 6, Hadith 1674 (IT)