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I'm making a few assumptions in asking my question. If they're incorrect, please comment.

Tefillat Shacharit is a substitute for the Shacharit sacrifice that was brought in the Temple. I have also heard that there was a time when people wore Tefillin the entire day, and at some point, this was scaled back to wearing it during the Shacharit prayers.

During the time of the Temple services, when did people wear tefillin? Was it the entire day, then? Does this mean that Cohanim wore tefillin while they were offering the sacrifices?

Between the time of the Temple destruction and the standardization of a Shacharit service as we have it, today (i.e. a specific order of prayers that we are currently saying), (by "destruction, I include the period between end of 1st and completion of the 2nd as well as after destruction of the 2nd.) when did people wear tefillin?

marked as duplicate by DonielF, Community Jul 30 '18 at 18:06

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  • I’ll have to dig it up, but towards the beginning of Erchin the Gemara says that the Kohanim wore their Tefillin while serving. There’s enough room on the head that the Kohen Gadol had no problem putting on his Tzitz and Tefillin at the same time, while putting the Migba’as over the Tefillin. – DonielF Jul 30 '18 at 16:47
  • Just a guess here, but maybe they donned the tefillin when they recited Shema in the morning? – ezra Jul 31 '18 at 1:53
  • @Ezra I originally thought of that. However, in viewing the answer in the duped question, they originally wore it all day. At the point that it was limited to Shacharit, it seems that the Siddur had been established. – DanF Jul 31 '18 at 13:55
  • @DanF I don't think they wore tefillin all day in ancient times. How would they be able to wear tefillin during dirty work in the fields, battle (for soldiers), etc.? You have to maintain a clean body while wearing tefillin, and I don't see how this would be possible under those conditions. – ezra Jul 31 '18 at 16:32