Messenger of Allah ﷺ said, "From among all the conditions which you have to fulfill, the conditions which make it legal for you to have sexual relations (i.e. the marriage contract) have the greatest right to be fulfilled."  

قَالَ رَسُولُ اللَّهِ ﷺ أَحَقُّ الشُّرُوطِ أَنْ تُوفُوا بِهِ مَا اسْتَحْلَلْتُمْ بِهِ الْفُرُوجَ