Question:
What is the du'a (supplication) one should say when they get married?

Answer:
Marriage is a great moment in one’s life. It is, therefore, important for the couple to turn to Allah in humble supplication in this crucial juncture of their life in order to receive His blessings; only thus they can hope to make their union a source of bliss for them as well as a great provision for their journey to Allah. Turning to Allah at every step of marriage is therefore the key to a blissful marital life: At the time of marriage contract those who solemnize marriage may offer the following supplication:

Allaahumma bariklahumaa wa ijma’ baynahumaa fee khayrin

(O Allah, bless them in their union and unite them on all that is good and beneficial).

When the couple come together to consummate the marriage, they should first offer two rak’as of nafl ( voluntary prayer) and then the husband should gently touch his wife’s forehead and pray for blessings by invoking the name of Allah:

Bismillaahi allaahumma barik lee fee ahlee wa barik laha fiyya wa ‘ijma baynanaa fee kharyin

Allaahumma innee as’aluka min kharyiha wa khayri maa jubilat alayhi.

(O Allah, may my spouse be a source of blessings for me; and may I be a source of blessings for her, and unite us both in all that is good and beneficial).

(O Allah, I ask of You to grant me the best in her, and the best inherent in her nature).

Having said this, it is important for them to engage in gentle conversation and start the foreplay and take time before engaging in intercourse. May Allah grant you both a blissful marriage-aameen.

Source: Islam.ca