Narrated [Abu Hurairah (RA)]: When the Prophet (ﷺ) congratulated a man on his marriage he would say, “Allah bless for you (your spouse), grant you blessing, and join you together in goodness.” [Reported by Ahmad and al-Arba’a. at-Tirmidhi, Ibn Khuzaimah and Ibn Hibban graded it Sahih (authentic)].
Bulugh al-Maram, Book 8, Hadith 972
This beautiful Dua in Arabic is:
بَارَكَ اَللَّهُ لَكَ , وَبَارَكَ عَلَيْكَ , وَجَمَعَ بَيْنَكُمَا فِي خَيْ