Brachos 2:4-5

Brachos 2:4

Workmen may recite Shema where they are working, even somewhere like in a tree or on a wall. This is not permitted when it comes to reciting Shemoneh Esrei, which requires concentration for an extended period of time.

Brachos 2:5

In the time of the Mishna, a groom would be exempted from reciting Shema from the wedding night until Saturday night, so long as he had not yet consummated the marriage. (His anxiety precludes having proper concentration.) Rabban Gamliel recited Shema on his wedding night. His students asked him, “Didn’t you teach us that a groom is exempt from reciting Shema?” He replied, “I refuse to refrain from accepting God’s authority even for a moment!”