Related do Berachot 3:2

The grooms and all [others] who are involved in [other] Mitzvot (commandments) are exempt from reading [the] Shema and from [the Amidah] prayer and from Tefillin (phylacteries), as it is said, “… when you sit in your house”, (Deuteronomy 6:7) which excludes grooms, “and when you walk on the way”, (Deuteronomy 6:7) which excludes those who are involved in mitzvot.

They have buried the dead [person] and lined up in a row. The [outer] row that sees the inner [row] is exempt [from saying the Shema] and the [outer] row that does not see the inner [row] is obligated [to say the Shema]. Rebbi Yehudah says, “If there is only one row there, then those who are standing there for the sake of honor [of the dead] are obligated [to say the Shema], [and those who are standing there] for the sake of the mourner are exempt [from saying the Shema].” [Later] they went down to eulogize [the dead person]. The people that see the inner row are exempt [from saying the Shema], and some say, “those who are behind them [are exempt as well].” And those that do not see the inner row are obligated [to say the Shema]. The one that says the eulogy and all of those who are involved in the eulogy stop [the eulogy] to read the Shema, but they do not stop [the eulogy] to pray [the Shmoneh Esreh]. It happened [once] that the Rabbis stopped [the eulogy] for the reading of the Shema and [the] prayer [of Shmoneh Esreh].