The Rabbis afforded great importance to the Mitzva of "Simchat Chatan Ve'kala," to rejoice and celebrate with a bride and groom at their wedding. The Rambam comments (Hilchot Avel 14:1) that although the Torah makes no specific reference to this Mitzva, it is included under the general category of "Ve'ahavta Le'rei'acha Kamocha" ("Love your fellow as yourself" Vayikra 19:18). Thus, one who helps bring joy to a bride and groom fulfills a "Mitzvat Asei Min Ha'Torah" the Biblical command to "love your fellow as yourself."
The Talmud records a debate regarding the manner in which this Mitzva may be fulfilled (Ketubot 17). Halacha follows the view of Beit Hillel, who allowed speaking in exaggerated or otherwise inaccurate terms while expressing praise to the bride and groom. Thus, Beit Hillel allows praising the bride as "Na'a Va'chasuda" ("charming and graceful") even if this description is inaccurate. We find several approaches taken to explain why Halacha allows speaking falsely in such a case. The Ritva (Rabbi Yom Tov Ashbili, famous Talmudic commentator, Spain, 1250-1330) attributes this law to the general principle allowing one to speak falsely in the interest of avoiding strife and contention. Hence, at a wedding, it is permissible to exaggerate the bride's qualities in order to endear her to the groom. Others explain that "Na'a Va'chasuda" refers not to the bride's physical appearance, but rather to her fine character.
The Mitzva of "Simchat Chatan Ve'kala" includes playing live music as part of a wedding celebration. While nowadays this may seem obvious, after the Temple's destruction many communities adopted a ban on music as an expression of grief over this calamity. Nevertheless, even these communities were required to play music at weddings in fulfillment of the Mitzva to rejoice with a bride and groom. (Sova Semahot Helek 1, page 181)
A distinguished Rabbi or other prominent figure fulfills this Mitzva through his very presence at the wedding, given the joy his presence brings to the bride and groom. (Sova Semahot Helek 1, page 183)
The Sages spoke very harshly about those who attend weddings and enjoy the food and drinks without participating in the celebration with the bride and groom. They warn that such a person, who rejoices only with himself and not with a bride and groom, will be excluded from the "five sounds" of celebration with which God will bless the Jewish people at the time of the final redemption. One who attends a wedding must therefore ensure to participate in the festivities to bring joy to the bride and groom, rather than bringing joy only to himself. (Masechet Berachot 6B)
The work Yalkut Yosef tells that Chacham Ovadia Yosef's father Rabbi Yaakov, called his grandchildren to his bedside before his death and told them that throughout his life he paid special attention to this Mitzva of Simchat Chatan Ve'kala. At that moment, just before his passing, he prayed that in the merit of this great Mitzva he should be granted a son who would "illuminate the eyes of Israel" with his Torah scholarship. Of course, this prayer was fulfilled through his son, Chacham Ovadia Yosef. This demonstrates the importance of this Mitzva and the immense reward that its proper observance earns for generations to come. (Sova Semahot Helek 1, page 181)
