A person who wears tefilin on right arm wants to have his tefilin checked. Until they are returned he needs to find temporary tefilin. His friend wears his tefilin on his left arm and offers to let him use his tefilin. Is there a way
to use his friend’s tefilin without changing the knot or anything else? Thanks!
What we need over here is that the yud on the side of the bayis should be facing towards your body. Therefore, if you are putting on a “righty’s” tefillin you would have to put it on backwards. Meaning that the mabarta, (the part of the tefillin where the strap runs through will end up being closer to your elbow than the tefillin itself. After that, the way the straps are wound it not as important. This way you will not have to remove the other person’s straps.