אורח חיים ע״בOrach Chayim 72

Se’if 1א׳

נוֹשְׂאֵי הַמִּטָּה וְחִלּוּפֵיהֶן וְחִלּוּפֵי חִלּוּפֵיהֶן, בֵּין אוֹתָם שֶׁהֵם לִפְנֵי הַמִּטָּה בֵּין אוֹתָם שֶׁהֵם לְאַחֲרֶיהָ, מֵאַחַר שֶׁלַּמִּטָּה צֹרֶךְ בָּהֶם, פְּטוּרִים. וּשְׁאָר הַמְלַוִּין אֶת הַמֵּת, שֶׁאֵין לַמִּטָּה צֹרֶךְ בָּהֶם, חַיָּבִים.

Laws of Those who Carry the Bier and Those who Comfort and Escort, Containing 5 S'ifim Those who carry the bier and the substitutes (ie. those who will take over for the first ones) and the substitutes for the substitutes, whether they are those who are in front of the bier (ie. who have not yet carried it) or those who are in back of it (ie. who carried it already), since they are needed for the sake of the bier, they are exempt. And the rest of the escorters of the dead (ie. they are just escorting it but not carrying it) who are not needed for the sake of the bier, are obligated.

Se’if 2ב׳

אֵין מוֹצִיאִין אֶת הַמֵּת סָמוּךְ לִקְרִיאַת שְׁמַע, שֶׁאֵין שְׁהוּת לְהוֹצִיאוֹ וּלְקָבְרוֹ קֹדֶם שֶׁיַּגִּיעַ זְמַן קְרִיאַת שְׁמַע. וְאִם הִתְחִילוּ לְהוֹצִיאוֹ, אֵין מַפְסִיקִין כְּדֵי לִקְרוֹת.

We do not bring out the body close to [the time for the] Recitation of the Sh'ma, in that there is not [enough] time to bring it out and to bury it before the time of the Recitation of the Sh'ma will arrive. But if they [already] began to bring it out, then we do not interrupt in order to recite [it].

Se’if 3ג׳

הָעָם הָעוֹסְקִים בְּהֶסְפֵּד בִּזְמַן שֶׁהַמֵּת מֻטָּל לִפְנֵיהֶם, נִשְׁמָטִים אֶחָד אֶחָד וְקוֹרִין וּמִתְפַּלְּלִין. אֵין הַמֵּת מֻטָּל לִפְנֵיהֶם, הֵם קוֹרִין וּמִתְפַּלְּלִין, וְהָאוֹנֵן יוֹשֵׁב וְדוֹמֵם.

The people occupied with the eulogy at the time that the body is lying before them slip away one by one and recite [the Sh'ma] and pray [the Amidah]. If the body is not lying before them, they recite [Sh'ma] and pray, and the pre-burial-mourner sits and is silent.