Allah said,

﴿وَإِنْ خِفْتُمْ أَلاَّ تُقْسِطُواْ فِى الْيَتَـمَى فَانكِحُواْ مَا طَابَ لَكُمْ مِّنَ النِّسَآءِ مَثْنَى﴾

(And if you fear that you shall not be able to deal justly with the orphan girls, then marry (other) women of your choice, two) Allah commands, when one of you is the caretaker of a female orphan and he fears that he might not give her a dowry that is suitable for women of her status, he should marry other women, who are plenty as Allah has not restricted him. Al-Bukhari recorded that `A'ishah said, "A man was taking care of a female orphan and he married her, although he did not desire to marry her. That girl's money was mixed with his, and he was keeping her portion from her. Afterwards, this Ayah was revealed about his case;

﴿وَإِنْ خِفْتُمْ أَلاَّ تُقْسِطُواْ﴾

(If you fear that you shall not be able to deal justly)'' Al-Bukhari recorded that `Urwah bin Az-Zubayr said that he asked `A'ishah about the meaning of the statement of Allah,

﴿وَإِنْ خِفْتُمْ أَلاَّ تُقْسِطُواْ فِى الْيَتَـمَى﴾

(If you fear that you shall not be able to deal justly with the orphan girls.) She said, "O my nephew! This is about the orphan girl who lives with her guardian and shares his property. Her wealth and beauty may tempt him to marry her without giving her an adequate dowry which might have been given by another suitor. So, such guardians were forbidden to marry such orphan girls unless they treated them justly and gave them the most suitable dowry; otherwise they were ordered to marry woman besides them.'' `A'ishah further said, "After that verse, the people again asked the Messenger of Allah (about marriage with orphan girls), so Allah revealed the Ayah,

﴿وَيَسْتَفْتُونَكَ فِى النِّسَآءِ﴾

(They ask your instruction concerning the women..) ﴿4:127﴾.'' She said, "Allah's statement in this Ayah,

﴿وَتَرْغَبُونَ أَن تَنكِحُوهُنَّ﴾

(yet whom you desire to marry) ﴿4:127﴾ refers to the guardian who does not desire to marry an orphan girl under his supervision because she is neither wealthy nor beautiful. The guardians were forbidden to marry their orphan girls possessing property and beauty without being just to them, as they generally refrain from marrying them (when they are neither beautiful nor wealthy).