muhsana is that of a chaste woman whose chastity is guarded. Allah, Exalted is He, says:

“And Mary, the daughter of Imrān, who guarded her chastity.”

He also says:

“Indeed, those who slander chaste, unsuspecting, believing women.”

These are chaste women. Hassān ibn Thābit said:

“Chaste and dignified, beyond suspicion,
She greets the dawn without feeding on unsuspecting women’s flesh.”

It was customary among the Arabs that free women were not known to commit fornication; rather, slave women were known for it. Thus:

“When the Prophet, may Allah bless him and grant him peace, took the pledge of Hind, the wife of Abū Sufyān, that she would not commit fornication, she said: ‘Does a free woman commit fornication?’”

This was not something known among them. Thus, in common usage, “free woman”—as opposed to a slave woman—came to mean a chaste woman, because a woman who was free rather than enslaved was known among them for chastity. The term ihsān therefore came to encompass freedom together with chastity, because slave women were not chaste. Likewise, Islam forbids indecency and wrongdoing. Similarly, a married woman’s husband safeguards her chastity, because he meets her needs and jealously guards her honour. Thus, the term “ihsān” came to encompass Islam, freedom, and marriage, although its fundamental meaning is chastity. A chaste woman is one whose private parts are guarded from anyone other than her husband, just as a chaste man abstains from anyone other than his wife. Since Allah has permitted marriage only to chaste women from among the Muslims and the People of the Scripture, and prostitutes are not chaste, Allah has not permitted marriage to them.

Further evidence of this is His statement:

“Provided that you give them their bridal dues, seeking chastity, neither committing fornication nor taking secret lovers.”

A musāfih is a fornicator who spills his semen with one woman after another.