Imaam Ibn al-Qayyim رحمه الله said: “For the people of sins there are three great rivers in which they will be purified in this world and if these do not suffice in purifying them, then they will be cleansed in the river of Hell-fire on the Day of Resurrection:
• The river of sincere repentance
• The river of good deeds that drowns the sins that surround it
• And the river of great calamities that are an expiation (for the sins of a sinner)
So if Allāh intends good for His slave, He makes him enter into one of these three rivers, so the slave comes purified and cleansed on the Day of Resurrection, not requiring the fourth purification (of Hellfire).” [Madarif us Saalikeen 312/1]
