Kommentar zu Bereschit 41:51

נשני, the construction of the word from the root נשש is similar to a similar construction of the root חנן in 33,11 where Yaakov explained to his brother Esau that he was looking at his children. The proof of this is the dagesh in the letter ש. [which effectively doubles that letter. Ed.] If the word nashani had been derived from the root נשה as in Isaiah 44,21 לא תנשני, or as in Lamentations 3,17, נשיתי טובה, where the root is one that loses its last root letter, the Torah here should have written nishani, instead of nashani. It then would have been parallel to the construction in Samuel II 19,27 עבדי רמני, rimani from the root רמה, to deceive, and other similar examples.

כי נשני אלוקים, what happened to him fore- shadowed what would happen in the future, as described in Isaiah 65,16 כי נשכחו הצרות הראשונות, “for the former troubles shall be forgotten

כי נשני, G’d granted me so much wealth and power that He enabled me to forget את כל עמלי, all the problems and setbacks I had experienced, and He has even made me forget all the members of my father’s household. [not including his father, of course. Ed.]