بَارَكَ اللَّهُ لَكَ، وَبَارَكَ عَلَيْكَ، وَجَمَعَ بَيْنَكُمَا فِي خَيْرٍ
Barakallahu laka, wa baraka 'alayka, wa jama'a baynakuma fi khayr
Que Allah te abençoe, derrame Suas bênçãos sobre ti e vos una a ambos no bem.
Say to newlyweds after marriage
The Prophet (PBUH) would say this dua for newlyweds, asking Allah to bless their union.