Berachos 2:4 - 2:5

נדבך – a layer of stones of a building such as “a course of unused timber for each three courses of hewn stone” (Ezra 6:4), and even though he is fearful that he might fall, and would not be able to focus (“have spiritual intentionality” during his recitation of the Shema) , the Sages did not require him to come down, for the Recitation of the Shema only requires spiritual intentionality for the first verse only (“Hear O Israel, the LORD our God, the LORD is One”).

מה שאינן רשאין לעשות כן בתפילה – for Prayer (the Recitation of the Amidah) is [a plea for] mercy and requires spiritual intentionality. Therefore, one descends (from above) and prays (recites the Amidah).

חתן – [A groom] who married a virgin

פטור מקריאת שמע לילה ראשון – is exempt from the Recitation of the Shema the first night (of his marriage) because of the grave concern that he might not find her to be a virgin. And I heard that he fears lest he might his genitals might be mutilated through his [initial] intercourse [with his wife] and it is his preoccupation with this Mitzvah. And All-Merciful One (God) said (Deuteronomy 6:7), “and when you are away” – in your “going” (the commandment for sexual intercourse with one’s [virgin] wife is tied to the command “be fertile and increase” – Genesis 1:27) – which obligates you but also commands one’s exemption [from the recitation of the Shema].

אם לא עשה מעשה – If he did not engage in sexual intercourse until Saturday night (after the conclusion of Shabbat) which is four nights that he was preoccupied [with his ability to perform his sexual obligations to his wife]. And from that point onwards, he becomes intimate with her and furthermore, is no longer preoccupied, and even though he has not yet performed his obligation [of intimacy with his wife], he is obligated to recite the Shema.