Hadiths: 7.71 and 7.72

7.71:
Narrated 'Ursa bin Az−Zubair: that he asked `Aisha, saying to
her, "O Mother! (In what connection was this Verse revealed):
'If you fear that you shall not be able to deal justly with
orphan girls (to the end of the verse) that your right hands
possess?" ( 4.3) Aisha said, "O my nephew! It was about the
female orphan under the protection of her guardian who was
interested in her beauty and wealth and wanted to marry her
with a little or reduced Mahr. So such guardians were
forbidden to marry female orphans unless they deal with them
justly and give their full Mahr; and they were ordered to
marry women other than them."`Aisha added, "(Later) the people
asked Allah's Apostle, for instructions, and then Allah
revealed: 'They ask your instruction concerning the women . .
. And yet whom you desire to marry.' ( 4.127) So Allah
revealed to them in this Verse that−if a female orphan had
wealth and beauty, they desired to marry her and were
interested in her noble descent and the reduction of her Mahr;
but if she was not desired by them because of her lack in
fortune and beauty they left her and married some other woman.
So, as they used to leave her when they had no interest in
her, they had no right to marry her if they had the desire to
do so, unless they deal justly with her and gave her a full
amount of Mahr."

7.72:
Narrated Sahl:
A woman came to the Prophet,, and presented herself to him
(for marriage). He said, "I am not in need of women these
days." Then a man said, "O Allah's Apostle! Marry her to me."
The Prophet asked him, "What have you got?" He said, "I have
got nothing." The Prophet said, "Give her something, even an
iron ring." He said, "I have got nothing." The Prophet asked
(him), "How much of the Qur'an do you know (by heart)?" He
said, "So much and so much." The Prophet said, "I have married
her to you for what you know of the Qur'an."