Tafsir of Qaf 50:9

Q: (9) And We sent down from the sky...

And We sent down from the sky water blessed—that is, possessing many benefits. This is a commencement to explain the manner of what was mentioned regarding the causing of every beautiful pair to grow. It is a conjunctive clause linked to “We caused to grow,” and what lies between them, according to the latter two interpretations, is a parenthetical sentence affirming what preceded it and alerting to what follows it.

So We caused to grow by it—that is, by that water—gardens—many in number, as the context requires, meaning trees bearing fruit—and the grain of the harvest—that is, the grain of the crops that are typically harvested, such as wheat, barley, and their like. The genitive construction (idafa) is based on the relationship between them. Harvested (al-hasid) is in the sense of “the harvested one,” acting as an adjective for an implied noun, as we have indicated. Thus, it is not of the category of “the congregational mosque” (masjid al-jami’), nor is it a metaphor of the former for the latter, as has been wrongly imagined. The specification of mentioning the growing of its grain is because it is [the objective] in essence.