يَوْمَ تَأْتِي كُلُّ نَفْسٍ تُجَادِلُ(Remember) the Day when every person will come pleading,meaning making a case in his own defence.عَن نَّفْسِهَاfor himself,means, no one else will plead on his behalf; not his father, not his son, nor his brother, nor his wife.وَتُوَفَّى كُلُّ نَفْسٍ مَّا عَمِلَتْand every one will be paid in full for what he did,meaning whatever he did, good or evil.وَهُمْ لَا يُظْلَمُونَand they will not be dealt with unjustly.meaning there will be no decrease in the reward for good, and no increase in the punishment for evil. They will not be dealt with unjustly in the slightest way