´It was narrated from Abu Hurairah:` that the Prophet used to say, when offering congratulations of the occasion of marriage: “Barak Allahu lakum, wa barak 'alaikum, wa jama'a bainakuma fi khair (May Allah bless you and bestow blessings upon you, and bring you together in harmony).”
Narrated Abu Hurairah: When the Prophet ﷺ congratulated a man on his marriage, he said: May Allah bless for you, and may He bless on you, and combine both of you in good (works).
Shaykh Umar Farooq Saeedi
Benefits and Issues: On such occasions of happiness, one should offer pure and Sunnah supplications as congratulations, which encompass all apparent and hidden meanings of affection, love, and increase.
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 2130