"and the L–rd smote every first-born in the land of Egypt": even (those first-born) from different places. And whence is the same derived for the first-born of Egypt (who were found) in different places? From (Psalms 136:10) "Who smote Egypt by their first-born" (wherever they were). Whence do I derive the same for the first-born of Cham, Kush, Put, and Lud? From (Ibid. 78:51) "He smote every first-born in Egypt, the first-fruit of their strength in the tents of Cham."