إِذَا تَزَوَّجَ أَحَدُكُمُ امْرَأَةً، أَوْ إِذَا اشْتَرَى خَادِماً فَلْيَقُلْ: ((اللَّهُمَّ إِنِّي أَسْأَلُكَ خَيْرَهَا، وَخَيْرَ مَا جَبَلْتَهَا عَلَيْهِ، وَأَعُوذُ بِكَ مِنْ شَرِّهَا، وَشَرِّ مَا جَبَلْتَهَا عَلَيْهِ، وَإِذَا اشْتَرَى بَعِيراً فَلْيَأْخُذْ بِذِرْوَةِ سَنَامِهِ وَلْيَقُلْ مِثْلَ ذَلِكَ)).
Transliteration
(when you marry a woman or buy a maidservant, you should say: (Allahumma innee as-aluka khayraha wakhayra ma jabaltaha AAalayh, wa-aAAoothu bika min sharriha washarri ma jabaltaha AAalayh.))(and if you buy a camel, then you should take hold of it’s hump and say likewise.)
Translation
(when you marry a woman or buy a maidservant, you should say:(O Allah, I ask You for the goodness within her and the goodness that you have made her inclined towards, and I take refuge with You from the evil within her and the evil that you have made her inclined towards.))(and if you buy a camel, then you should take hold of it’s hump and say likewise.)
Source
Hisnul Muslim (Fortress of the Muslim), No. 191 — chapter “The groom’s supplication on the wedding night or when buying an animal”. hisnmuslim.com
Related Duas
((بَارَكَ اللَّهُ لَكَ، وَبَارَكَ عَلَيْكَ، وَجَمَعَ بَيْنَكُمَا فِي خَيْرٍ)).
(May Allah bless for you (your spouse) and bless you, and may He unite both of you in goodness.)
Hisnul Muslim · No. 190
((بِسْمِ اللَّهِ، اللَّهُمَّ جَنِّبْنَا الشَّيْطَانَ، وَجَنِّبِ الشَّيْطَانَ مَا رَزَقْتَنَا)).
(In the name of Allah. O Allah, keep the devil away from us and keep the devil away from what you have blessed us with.)
Hisnul Muslim · No. 192