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).”
أَنَّ النَّبِيَّ ﷺ كَانَ إِذَا رَفَّأَ قَالَ بَارَكَ اللَّهُ لَكُمْ وَبَارَكَ عَلَيْكُمْ وَجَمَعَ بَيْنَكُمَا فِي خَيْرٍ