As for things without knowledge, their plural takes feminine agreement, as when you say: “The wealth—I gathered it,” and “The stones—I threw them.” Thus, mā (“what”) is used for things without knowledge and for the attributes of beings endowed with knowledge. Hence it can denote an entire class, since a class encompasses its members by virtue of their attributes. As He says:

“Marry such women as are pleasing to you.”

That is, those who are pleasing—the pleasing among women. Since He intended to speak of those characterized as pleasing, focusing on this attribute rather than merely on the individuals themselves, He used mā. Had He used man (“who”), the focus would have been merely on the individuals, with the attribute serving to identify them rather than being intended in its own right, even if it ceased to apply. This is like saying: “Someone who knows came to me,” “Someone who was in the mosque yesterday came to me,” or “Someone who did such-and-such came to me,” and similar expressions. The intent is to speak of the individual, while the relative clause serves to identify them, even if that attribute no longer applies.

Another example is His saying:

“By the heaven and the One who built it,”
“by the earth and the One who spread it out,”
“and by a soul and the One who proportioned it.”

According to the correct view, mā here is a relative pronoun, and the meaning is: by its Builder, its Spreader, and its Fashioner. But when He says:

“Successful indeed is the one who purifies it,”
“and failed indeed is the one who corrupts it,”

He uses man, because the intent is to speak of the individual’s success, even though their acts of purification or corruption have already passed in this world. The oath in those earlier verses is therefore by the One bearing the attribute: He swears precisely by this One, while the attribute