Богатое приданое все равно, что постель полная колючек. This proverb is used to explain that it's better to marry a poor person with love than to marry a rich one for his/her money and have a miserable life with him/her. Dowry in Russian is "приданое", and the great dowry here means " богатое приданое" ) The proverb is used to explain that a man should not marry a woman for her wealth ( or vise versa) , because this kind of marriage is just like a bed full of brambles : It only causes pain and misery .

Well, I suggest you get into a bed full of brambles. then you'll understand exactly what this means.