What are the connotations of "al Yadecha"?
Why does the Torah refer to the Tefilin she'be'Rosh as 'Totafos'?
Rashi (citing Sanhedrin, 4a): The word is made up of two foreign words - the Kaspian word 'Tat' and the African word 'Pas', both of which mean 'two' - hinting at the four Parshiyos that comprise the Tefilin shel Rosh. 1
Though the question remains why the Torah only does this by Tefilin, and why specifically in connection with the Tefilin shel Rosh and not the Tefilin shel Yad?
Having taught the Mitzvah of Tefilin in Parshas Bo, why does the Torah repeat it here?
Ramban (on Pasuk 7): In order a. to add the obligation of tying the Tefilin to one's arm and b. to hint at the knot of the Tefilin - which the Chachamim learn from Halachah le'Moshe mi'Sinai.