The people of sins have three great rivers to purify themselves of in this life. If they are insufficient in purifying them, then they will be purified in the river of Hell on the Day of Resurrection: 1) The river of sincere repentance. 2) The river of good deeds that drown the surrounding sins. 3) The river of great calamities that expiate. If Allah intends good for His servant, He makes him enter one of these three rivers, and then he appears on the Day of Resurrection good and purified, thus not requiring the fourth purification. [Madarij al-Salikin, Ibn al-Qayyim (1/312)] في الدنيا ثلاثة أنهار لتطهير الذنوب

The people of sins have three great rivers to purify themselves of in this life. If they are insufficient in purifying them, then they will be purified in the river of Hell on the Day of Resurrection: 1) The river of sincere repentance. 2) The river of good deeds that drown the surrounding sins. 3) The river of great calamities that expiate. If Allah intends good for His servant, He makes him enter one of these three rivers, and then he appears on the Day of Resurrection good and purified, thus not requiring the fourth purification. [Madarij al-Salikin, Ibn al-Qayyim (1/312)] في الدنيا ثلاثة أنهار لتطهير الذنوب