Related for Berakhot 2:5
חָתָן פָּטוּר מִקְּרִיאַת שְׁמַע בַּלַּיְלָה הָרִאשׁוֹן עַד מוֹצָאֵי שַׁבָּת, אִם לֹא עָשָׂה מַעֲשֶׂה. מַעֲשֶׂה בְּרַבָּן גַּמְלִיאֵל שֶׁקָּרָא בַלַּיְלָה הָרִאשׁוֹן שֶׁנָּשָׂא. אָמְרוּ לוֹ תַּלְמִידָיו, לֹא לִמַּדְתָּנוּ, רַבֵּנוּ, שֶׁחָתָן פָּטוּר מִקְּרִיאַת שְׁמַע בַּלַּיְלָה הָרִאשׁוֹן. אָמַר לָהֶם, אֵינִי שׁוֹמֵעַ לָכֶם לְבַטֵּל מִמֶּנִּי מַלְכוּת שָׁמַיִם אֲפִלּוּ שָׁעָה אֶחָת:
A bridegroom is exempt from the recital of the Shema the first night, until motzai Shabbath if he had not performed the act. [A bridegroom who married a virgin is exempt from the recital of the Shema the first night, being preoccupied lest he not find her to be a virgin. And I have heard that (his preoccupation is) the fear that he might become kruth shafchah (mutilated) through intercourse, this being "preoccupation of a mitzvah." And Scripture states (Deuteronomy 6:7): "and in your walking upon the way" — It is in your (mundane) "walking" that you are obliged to recite it, but not in that entailed by a mitzvah. "if he had not performed the act": if he had not had intercourse until motzai Shabbath, his "preoccupation" lasting four nights [from the customary day (Wednesday) of the wedding for a virgin]. After that time, he is "familiar" with her and no longer preoccupied, so that even if he had not yet performed the act, he must recite the Shema.] It happened that R. Gamliel recited the Shema on his wedding night, at which his disciples said to him: "Did our master not teach us that a bridegroom is exempt from the Shema?" He answered: "I will not heed you to divest myself of the yoke of the kingdom of Heaven for even a short while!"