"And marry the unmarried among you" means: every woman who has no husband.

Muhammad said: It is said: an ayyim (unmarried) woman, and an ayyim man, and an armal (widower) man, and an armala (widow) woman. "And the righteous among your male slaves and female slaves" means: the Muslim slaves, both male and female. This is a concession, and it is not obligatory for a man to marry off his female slave or his male slave. "If they should be poor, Allah will enrich them from His bounty."

Yahya: On the authority of Abd al-Aziz ibn Abi Rawwad; that the Messenger of Allah, peace be upon him, said: "Seek wealth in this verse: 'If they should be poor, Allah will enrich them from His bounty.'"

Yahya: On the authority of Sa'id, from Qatada; that Umar ibn al-Khattab used to say: "I have never seen the likes of a man who does not seek wealth in marriage, while Allah says: 'If they should be poor, Allah will enrich them..."