when you marry a woman or buy a maidservant, you should say: (Allahumma innee as-aluka khayraha wakhayra ma jabaltaha 'alayh, wa-a'oothu bika min sharriha washarri ma jabaltaha 'alayh.))(and if you buy a camel, then you should take hold of it’s hump and say likewise.
Meaning: 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: Hisn al-Muslim (Fortress of the Muslim) — Saʿīd ibn ʿAlī al-Qaḥṭānī (The groom’s supplication on the wedding night or when buying an animal)