This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Among Rabbeinu Tam's rulings and glosses, one detail continues to be practiced today independent of the broader Tosafist method he is best known for: the specific order in which four biblical passages are placed inside tefillin, the leather boxes containing scripture worn by observant Jews during weekday prayer. Rabbeinu Tam held that the correct order differed from the sequence attributed to his own grandfather Rashi, a documented disagreement between grandfather and grandson over a point of religious practice rather than of legal theory alone.
The order attributed to Rashi remains the more common practice, but the alternative order bearing Rabbeinu Tam's own name survives as a live, minority practice observed by some communities alongside it, often worn in addition to Rashi's order by especially observant individuals rather than replacing it outright. That two orderings, disputed by grandfather and grandson eight centuries ago, both remain in active use today rather than one displacing the other is itself the documented outcome of the disagreement.
That a specific procedural dispute between Rashi and his own grandson over the order of scripture inside tefillin never resolved into a single settled practice, and instead left two orders in parallel use into the present day, marks Rabbeinu Tam's tefillin order as a documented case where a scholarly disagreement became a durable practical alternative rather than being settled one way or the other.