4 chains merged

as above (the sub narrators are different). Abu Huraira qualified the three children referred to in the above mentioned Hadith as not having reached the age of committing sins (i.e. age of puberty) .

Three (children) who die in childhood.

"The Messenger of Allah said: 'There is no Muslim, three of whose children die before reaching puberty, but Allah will admit him to Paradise by virtue of His mercy towards them."'

“I heard the Messenger of Allah (ﷺ) say: ‘There is no Muslim, three of whose children die before reaching the age of puberty, but they will meet him at the eight gates of Paradise and whichever one he wants he will enter through it.’”