Shaykh al-Islām—may Allah have mercy on him—was asked:

A man proposed to the daughter of a man known for his uprightness and agreed with him on the dowry, part payable immediately and part deferred. He delivered the immediate portion to her father four years ago and has continued to provide them with financial support, though nothing had been put in writing between them. Then another man proposed to her, offered a larger dowry, and prevented the first husband from proceeding?

He replied:

It is not permissible for a man to propose marriage to a woman whose proposal from his brother has been accepted and whose family has settled on him. The leading scholars agree on this, as it is authentically established that the Prophet, may Allah bless him and grant him peace, said:

“It is not permissible for a man to propose marriage to a woman to whom his brother has already proposed.”

Whoever does this, and whoever assists him, must receive a punishment that deters them and others like them from doing so. Is the second man’s marriage valid or invalid? Scholars hold two views on this within the schools of Mālik, Ahmad, and others.

He—may Allah have mercy on him—was also asked:

A man visits his brother’s wife and the daughters of his paternal and maternal uncles. Is this permissible for him or not?

He replied:

He may not be alone in seclusion with any of them. However, if he enters with someone else, without seclusion or grounds for suspicion, that is permissible for him. And Allah knows best.