Say this to the one who marries

It is recommended that it be said to the one who has been married: Baarakal laahu laka wa Baaraka 'alayka wa jama'a bainakumaa fii khair

 ويستحب أن يقال للمتزوج : بَارَكَ اللَّهُ لَكَ وَبَارَكَ عَلَيْكَ وَجَمَعَ بَيْنَكُمَا فِي خَيْرٍ

Narrated Abu Hurayrah: When the Prophet (sallallaahu alayhi wa sallam) 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).

[Sunan Abu Dawud -The Book of Marriage - Chapter: What is said to the one who marries - Hadith No. 2130]