Is a man permitted to marry a slave woman if he can only afford the Mahr of a free woman by paying a Mahr significantly exceeding the established rate (Mahr al-Mithl) without facing undue hardship?
Chapter on What is Prohibited to Marry and Combining Between Them and Other Matters
Al-Mughni
Book of Marriage
Primary text
The ruling is that if a man can afford a Mahr exceeding the Mahr al-Mithl for a free woman, and this payment does not cause him hardship, he is not permitted to marry a slave woman. This is supported by the verse: "And whoever among you cannot afford to marry free, believing women..." (Quran 4:25), implying that one who can afford the standard rate is capable. If he can afford the higher Mahr without hardship, he is deemed capable of marrying a free woman, and thus should not enter into the marriage of a slave woman to avoid rendering his potential offspring enslaved, just as he would not resort to that if he could afford the standard Mahr.
Supporting text
The Shafi'i scholars permit this, drawing an analogy to making Tayammum (dry ablution) when water is only available at an inflated price compared to its standard value. They argue that if one can afford the higher Mahr, they should be allowed to marry the slave woman, similar to how one permitted to use Tayammum when water is overpriced.