And marry those among you who are single and those who are fit among your male slaves and your female slaves; if they are needy, Allah will make them free from want out of His grace; and Allah is Ample-giving, Knowing. (Holy Qur'an 24:32)
If someone of good character and conduct proposes to your daughters, marry them. If you do not, there will be mischief and great corruption on Earth. (Kulayni and Tirmidhi)