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).
Related hadith on this topic
Explanation & Benefits
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