“ויקח מאבני המקום וישם מראשותיו וישכב במקום ההוא…ויקח את האבן אשר שם מראשותיו”
Rashi explains that stones were quarreling with one another. Each stone wanted to be the pillow for Yaakov. Hashem made a miracle and they all turned into one large stone.
The מחבר (או”ח סימן מ”ב סעיף א’) writes that one may not turn his teffilin shel rosh into a shel yad. One may not even take the retzuos from the shel rosh to use for the shel yad. The reason is מפני שאין מורידין מקדושה חמורה לקדשה קלה – something on a higher level of kedusha may not be brought down to a lower level of kedusha. ושל ראש קדושתו חמורה שרבו של שקי בשל ראש – since the shel rosh has most of the letters of the name שקי it is considered to have more kedusha.
The מגן אברהם (ס”ק ג’) adds that if the רצועה של יד snapped near the קשר, and he wants to sew it back on and use the lower end of the רצועה to make the קשר since that side is stronger, he may not do so. By doing so it is considered מוריד מקדושתו since it originally had the קשר והיוד and now it will only be used to wrap around the fingers. Rather that piece of the רצועה needs גניזה. If the remaining רצועה is not long enough then it does not have to be wrapped around the arm so many times.
The אליהו רבא בשם זקנו הגאון מהר”ש disagrees with the מגן אברהם and holds that it is permitted to switch around the sides of the רצועה. He brings a proof from this week’s parsha that all the stones turned into one stone. How did turning it into one stone solve the problem, there is still going to be jealousy over which side of the rock Yaakov Avinu will rest his head? We learn from here that sides do not make a difference. Since it is one object it is all equal.
However he then questions this halacha from סימן י’ where the לחם חמודות ושל”ה explain that the reason for an עטרה is to make sure the tallis is put on the same way every time. The part that is by the head has more kedusha than the other part of the tallis. We see from this halacha that even though it is one object it is still possible to say מורידין מקדושתו therefore the same should apply to the רצועה של תפילין.
The שערי תשובה says that one cannot bring a proof from the stones by Yaakov Avinu. It is possible that the stones didn’t just become attached to form one large rock. Rather the rock was composed of all the rocks. Meaning the one rock was made from all the rocks mixed together. Therefore Yaakov Avinu was actually placing his head on all of the rocks at the same time. By the רצועה however there are different parts to it and it is therefore possible to say that one side has more kedusha than the other.
The Mishnah Berurah brings many poskim who hold that even if one does not want to sew the torn רצועה back on, never-the-less he should not switch around the רצועה. Since the top part was closer to the קשר it has more kedusha than the part that was further away from the קשר. The Mishna Berurah paskens that one should be stringent not to change the higher part of the רצועה to the lower side unless he has no other רצועה and he cannot make a קשר on that same side since it is to weak and worn out.
Prepared by R’ Avrohom Yehoshua Ziskind
 Sources:משנה ברורה,שערי תשובה,חבצלת השרון