Wa aleikum salam wr wb
Quran-Al Imran
''Allah would not leave the believers in that [state] you are in [presently] until He separates the evil from the good. Nor would Allah reveal to you the unseen. But [instead], Allah chooses of His messengers whom He wills, so believe in Allah and His messengers. And if you believe and fear Him, then for you is a great reward.''
Allah has informed us of his punishment of the previous nations for their wickedness such as the people of Nuh, and 'aad, Thamud, the people of Lut, the people of the city of Madyan, and the people of Fir'aun (Pharoah) in this world, and He has informed us of the punishments which await them in the next world. Thus, the believer who had been hiding his belief from the people of Fir'aun said, as Allah tells us in the Qur'an:
[O, my people, verily I fear for you something like the days of the nations who came before, something like the punishment which befell the people of Nuh, 'aad, Thamud, and those who came after them. Allah does not intend any oppression of His slaves. And O, my people, verily I fear for you the day of calling to one another, on that day you will turn your backs and run in fear, and there will be none who can protect you from Allah. Whosoever Allah sends astray has no one whatsoever who can guide him.] Qur'an 40/30-33
And Allah said in another aya about the punishment in this world:
>[Such is the punishment, and the punishment in the next world is greater, if only they knew.] Qur'an 68/33
>[We will punish them twice, and then they will be returned to a mighty torment. ] Qur'an 9/101
>[We will give them a taste of the minor punishment before the greater punishment, that they might turn back (i.e. to what is right)] Qur'an 32/21
I know there is much evil on this Earth, but Allah never fails His word, after He will see our deeds and separate the bad from the good ones, the reward will be equal to whatever we gained or according to His Mercy.Sometimes we fail to understand this, because we want justice and good things to be completed in our notion of real time, but this life is a short journey and a test, while the real and foreverlasting one will be the afterlife.
And Allah knows best.