פירושים על בראשית 27:3: רש״י, רמב״ם, אבן עזרא ועוד

שא נא — The word שא means sharpen, similar to what שא read in the Mishna (Beitzah 28a) “One may not sharpen the knife in the usual manner but one may sharpen it by passing it (משיאין) over another”. Isaac said to Esau, “Sharpen your knife and slaughter an animal according to the regulations so that you may not give me to eat נבלה” (i.e. the flesh of animal that is not killed according to the ritual rules) (Genesis Rabbah 65:13).

שא נא כליך, the reason for the repetition of the word נא both in verse 2 and verse 3 is similar to that in Genesis 12,11 where I have already explained it. [not found there. Ed.]

שא נא כליך, so that you will not return with your mission unaccomplished.