Once upon a time there was a rasha that came to a tzaddik saying he wanted to learn Torah. Truly, he did not want to learn, because all he wanted was to disturb the tzaddik. Anyway, the tzaddik said to the rasha: “Let us begin by learning the Alef-Bet. This is the letter Alef“. And the rasha answered him: “How do you know that this is the letter Alef?”. The tzaddik then took the rasha‘s ear and pulled on it. The rasha said: “Ouch, you are stretching my ear!”. And the tzaddik replied: “Who told you this is your ear?” From this mashal/story we learn the nature of the yetser hara/evil inclination. See, she knows well the yetser hatov/good inclination. She says to it: “Go do a mitzva, go study Torah or pray”. However, deep down it does not want any mitzva done. Therefore, when the person goes to fulfill a mitzva, like in the tefillah, the yetser hara comes and disturbs her. Now, the yetser hatov also knows very well the yetser hara, after all they are always at war with one another. So, it says to the yetser hara that this time she is indeed allowed to lead a person into doing an averah (chaz v’shalom). Then, the yetser hara gets happy and comes very close to make a person transgress, yet before that, the yetser hatov pulls away the yetser hara as if it was “pulling on its ears”, moving her far from the averah, leaving it dejected and subjugated. And regarding the words in the parsha Beha’alotecha, הצר הצרר אתכם Chatzer hatzorer etchem, “The enemy who oppresses you” (Bamidbar 10:9), the Shlach HaKodesh says: “These [words] are a very clear allusion to the yetser hara, since no enemy disturbs us more than the Samech-Mem [Satan]… There is a constant struggle between man and his yetser hara. At times, man wins over the yetsar hara, and in other moments, the powers of the Samech-Mem win over man. In any manner, both are constantly involved in a state of war”. Truly, the yetser hara is the “enemy” that brings that which is מרת morat, (“bitter”) to man. And this term has gematriaatbash of 640, the same as the pasukChatzer hatzorer etchem. However, if man learns to subjugate the yetser hara, he then walks in the דרך הקדש derech ha-kodesh, (“holy path”), with gematria 633, the same as the gematria albam of Chatzer hatzorer etchem.