Saying the Parsha of Shema, Kadeish and Vehaya while wearing Tefillin:

Parshiyos of Shema: One is required to recite the Parshiyos of Shema and Vehaya Im Shamoa while wearing Tefillin.[1] Nevertheless, if one already said Shema, he is not obligated to repeat specifically these Parshiyos when putting on the Tefillin afterwards and rather any Mizmor may be recited.[2] Nonetheless, when wearing Rabbeinu Tam Tefillin, the custom is to recite Shema with them even though he already said Shema in Rashi Tefillin.[3] [Seemingly, based on this custom, one should always say Shema when wearing Rashi Tefillin, even if he already said Shema previously.[4]]

Parshiyos of Kadeish and Vehaya: Some[5] are accustomed[6] to read also the Parshiyos of Kadeish and Vehaya Ki Yeviacha while wearing the Tefillin. They are to read the Parshiyos of Kadeish and Vehaya Ki Yeviacha immediately after wearing the Tefillin, while the Parshiyos of Veahavta and Vehaya Im Shamoa are read in Shema during Davening.[7] The above is read while wearing Rashi Tefillin.[8] Upon wearing Tefillin Rabbeinu Tam they repeat all four Parshiyos, starting from Kadeish and Vehaya Ki Yeviacha.[9]

The Chabad custom: The Chabad custom is to read the Parshiyos of Kadeish and Vehaya Ki Yeviacha only while wearing Tefillin of Rabbienu Tam and not while wearing Rashi Tefillin.[10] It is read in the following order: Shema/Veahavta, Vehaya Im Shamoa, Kadeish and Vehaya Ki Yeviacha.[11]

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[1] M”A 25/6 based on Sifri; Bach 38 in name of teacher Rav Feivish; Shlah, brought in M”A 25/6; Or Tzaddikim in name of Ramban and Rav Chaim Vital, brought in Shaareiy Teshuvah 38/3 “One is obligated to read all four Parshiyos”; Levush 58/2; See Levushei Mordechai 3/5 in name of Maharam Shick 23 that from the Poskim who write one is to recite Shema with Rabbeinu Tam [see footnotes below] it is implied that just like there is Eiduis Sheker to recite Shema without Tefillin, so too it is Eidus Sheker to wear Tefillin without saying Shema.

[2] Admur 66/11 and Siddur Admur [letter 22 Raskin] and M”A 66/12 that one who is wearing Tefillin after Davening is to say with them a Mizmor. This clearly implies that there is no obligation to recite Shema while wearing Tefillin once the obligation of Shema has already been fulfilled. So learns Chikrei Halachos 6/76; Siddur Raskin footnote 72 [p. 81] that only the Shema of the obligation requires Tefillin. However, see Admur 34/5 that rules that although one is not obligated to read Shema with the Rabbeinu Tam Tefillin, if he is troubled that he said Eidus Sheker according to Rabbeinu Tam [when he said Shema in Rashi Tefillin], then he is to repeat Shema while wearing Rabbeinu Tam. Furthermore, in Siddur Admur regarding Rabbeinu Tam he says to say Shema while wearing them, [however earlier in letter 17 Siddur Raskin Admur simply writes to learn with Rabbeinu Tam and does not mention the need to say a Mizmor]. This implies that one should say Shema with the Tefillin. Vetzaruch Iyun, as why by the Rashi Tefillin Admur writes there is no need to repeat Shema while by Rabbeinu Tam he writes that one could/should do so. Perhaps however the explanation is that in truth from the letter of the law there is no need to repeat Shema while wearing Tefillin, as it was already said. However the custom is to do so, and this would apply for both Rashi and Rabbeinu Tam.

Other opinions: Some Poskim rule that one is to recite Shema when he wears the Tefillin, even if he has already recited it [without Tefillin]. [Levush 58/2; Levushei Mordechai 3/5 in name of Maharam Shick 23]

[3] Siddur Admur in previous footnote; see Admur 34/5 brought in previous footnote; Siddur Raskin footnote 72 [p. 81]; P”M 25 A”A 6; Machatzis Hashekel 34; Shaareiy Teshuvah ibid; M”B ibid in name of Artzos Hachaim [regarding repeating all four Parshiyos in Rabbeinu Tam, not regarding the order]; See Os Chaim Veshalom 25/6

[4] Levushei Mordechai 3/5 in name of Maharam Shick 23 that from the Poskim who write one is to recite Shema with Rabbeinu Tam it is implied that just like there is Eiduis Sheker to recite Shema without Tefillin, so too it is Eidus Sheker to wear Tefillin without saying Shema.

[5] Bach 38 in name of teacher Rav Feivish; Shlah, brought in M”A 25/6; Or Tzaddikim in name of Ramban and Rav Chaim Vital, brought in Shaareiy Teshuvah 38/3 “One is obligated to read all four Parshiyos”; Machazik Bracha 38; Ben Ish Chaiy Vayeira 25; Kaf Hachaim 25/30; M”B 25/16; This custom is recorded in Siddur Admur regarding Tefillin of Rabbeinu Tam

[6] Wording of Admur in Siddur; M”B ibid; M”A ibid rules based on Sefri Parshas Vaeschanan that it is not an obligation to say the Parshiyos of Kadesh and Vehaya Ki Yeviacha, and only the Parshiyos of Veahavta and Vehaya must be said.

Other opinions-Obligation: Some Poskim rule it is an obligation to recite all four paragraphs while wearing Tefillin. [Bach ibid and Shelah ibid, brought in M”A ibid; Or Tzaddikim ibid] The M”A ibid negates their opinion based on the Sifri ibid

[7] Or Tzaddikim in name of Ramban and Rav Chaim Vital, brought in Shaareiy Teshuvah 38/3; Machazik Bracha ibid; Ben Ish Chaiy ibid; Kaf Hachaim ibid; M”B ibid

The reason: The reason it is read in this order is because this follows the order that the Parshiyos are written in the Torah. [Poskim ibid]

[8] Poskim ibid all refer to the Rashi Tefillin

[9] P”M 25 A”A 6; Machatzis Hashekel 34; Shaareiy Teshuvah ibid; M”B ibid in name of Artzos Hachaim [regarding repeating all four Parshiyos in Rabbeinu Tam, not regarding the order]; Siddur Admur “One is to read Kerias Shema while wearing Rabbeinu Tam and some are accustomed to also say the Parshiyos of Kadesh and Vehaya Ki Yeviacha.” See Shaar Hakolel 11/41 for why Admur records that only “some are accustomed”

[10] Admur in the Siddur does not record the Parshiyos of Kadesh and Vehaya Ki Yeviacha while wearing the Rashi Tefillin during the prayer, and neither does he give any directive to say it. It is only recorded in Admur in reference to those who wear Rabbeinu Tam; Shulchan Hatahor 38/9 and Chakal Yitzchak 5 record that since we rule like the M”A ibid, one is not required to say these paragraphs in both Rashi and Rabbeinu Tam, and if one says it while wearing one pair of Tefillin it is not required to be said in the other pair. See Piskeiy Teshuvos 25 footnote 111

[11] Sefer Haminhagim p. 38 [English] based on a directive of the Rebbe; Custom of many recorded in Piskeiy Teshuvos 25/14; Admur in the Siddur does not record the order for those who say all four Parshiyos

The reason: See Siddur Raskin p. 195 [footnote 505] that perhaps this is due to that the main paragraphs of recital are the paragraphs of Shema.