Genesis 20:1-5 (translation mine)
And Abraham journeyed from there to the land of Negeb, and dwelt between Kadesh and Shur, settling in Gerar.
2 Now of his wife Sarah Abraham had said, “She is my sister.” Therefore Abimelech, king of Gerar, sending for her, took Sarah for his own wife. 3 But God came to Abimelech in a dream by night, and said to him, “Behold, you shall die on account of the woman you have taken: for she is the wife of a husband already.” 4 Abimelech, therefore, did not approach her, but said, “Lord, would you really kill a nation that is innocent? 5 Did he not say to me, ‘She is my sister?’ She herself said to me, ‘He is my brother.’ In the sincerity of my heart and in the cleanness of my hands did I do this.”
Why did Abimelech conflate his own punishment with that of a whole nation?