And those who have no means for marriage may keep chastity until Lord Allah enriches them from His Bounty; and those who seek contract of freedom from among whom your right hands possess, then you write a contract of freedom for them if you know there is goodness within them; and you give them from the wealth of Allah which He has provided for you. And you don’t compel your slave girls for prostitution to seek the temporary interests of the worldly life if they desire chastity; and if anyone is forced, then indeed Allah is the Forgiving and Merciful after their compulsion.
Lord has ordered to give dowry from male to the guardian of female for bringing up the dignity of women into the society as explained in verse 2: 229. So the male who is not able to give dowry to the female guardian should wait until he can meet it. See explanation 1: 2; 2: 186, 256, and 4: 34.