The Very Last Man

Yesterday my dad told me a story that shook me to the core..

I don't know the particular hadith, but it's about the last man on earth to enter el-Jenna (Heaven).
Imagine, the very last man on earth to be granted el-Jenna.. how bad a person could he have been in his life to be the very last one to receive Allah's forgiveness & be blessed with eternal paradise?

So the hadith says that this man (a Muslim sinner) has served his time in Hell, Allah graced him with his forgiveness. Allah allowed him to walk his way towards heaven, but under no circumstance should he ask Allah any questions (that was the condition).
So the man agrees, but he can't resist not asking.. so he asks not once, not twice but three times, and Allah answers him all three times, tolerantly.
Then the man asks Allah to permit him to stand by the door of el-Jenna! It's all he'll ever ask, and it's all he ever wants (he realizes he has broken his promise to Allah three times).
So Allah replies that he will grant him what is 10 times worth el-dunya (life).

It got me thinking, if the very last man to enter el-Jenna is released from Hell and rewarded what is worth 10 times el-dunya, how generous is Allah? & how does Allah reward those who dedicated their lives to worshipping him?

& what is el-dunya worth when everything in it is mortal?

& why are we so blind to see that el-dunya we're living now is mortal?

& that one lifetime in el-dunya does not even equal a fraction of a second in the afterlife?

Subhan Allah!


PS

If any of you knows where I can find a source for the hadith please let me know.