1,455. The Marriage Bracha
Hilchos Ishus 3:23
When a man consecrates a woman, he – or his agent if an agent is consecrating the woman for him – recite a bracha beforehand, as one does before performing any mitzvah. If he neglected to recite the bracha before consecrating the woman, he does not recite it after. Doing so would constitute reciting a bracha in vain because the deed has already been done.
Hilchos Ishus 3:24
The bracha recited is that God has sanctified us with His commandments and separated us from prohibited relationships; He has prohibited betrothed women to us and permitted us those whom we marry through chuppah (the marriage canopy) and kiddushin. Blessed is God, Who sanctifies Israel. The custom is to recite this bracha over a cup of wine or beer. If wine is available, then the bracha over the wine should be recited first, followed by the marriage bracha, and then the woman is consecrated. If wine and beer are unavailable, then the marriage bracha is recited by itself.