Reference for Eruvin 190:21
ואיבעית אימא דכ"ע שבת זמן תפילין הוא והכא במצות צריכות כוונה קמיפלגי ת"ק סבר לצאת בעי כוונה
No, all may hold the view of R'Samuel son of R'Isaac, but the point at issue between them<span class="x" onmousemove="('comment',' R. Gamaliel and the first Tanna in our MISHNAH:');"><sup>39</sup></span> is whether the Sabbath is a time for tefillin, the first Tanna maintaining that Sabbath is a time for tefillin<span class="x" onmousemove="('comment',' Cf. Supra p. 660, n. 10. As the commandment is performed by the wearing of one pair, only one pair at a time may be worn.');"><sup>40</sup></span> while R'Gamaliel maintains that Sabbath is no time for tefillin.<span class="x" onmousemove="('comment',' And the permissibility of carrying them into a place of safety is based on their suitability as ornaments. Hence his ruling that as ornaments two pairs at a time may also be worn.');"><sup>41</sup></span>