Tafsir of Al-Inshiqaq 84:17

And {what it gathers} means what it collects and brings together. It is said, "He gathered (wasqahu) it, so it became collected (ittasaqa) and assembled (istawsaqa)," meaning he gathered it, so it became gathered. It is also said, "Mawsūq food," meaning gathered food, and "Mustawsiq camels," meaning gathered together. The poet said:

We have young she-camels, true to their age, Gathered together (mustawsiqāt), having found no driver.

From this comes the wasq (measure), referring to the collected āṣwu (plural of ṣā‘), which is sixty *ṣā‘*s, or the load of a camel, due to its being gathered upon its back.

The word mā (what) can be interpreted as either an infinitive particle (maṣdariyyah) or a relative pronoun (mawṣūlah), with the majority favoring the latter. The resumptive pronoun (‘ā’id) is elided, meaning: "And by that which it gathers." It refers to whatever gathers during the night and returns to its place, such as beasts and others.

According to Mujahid, it refers to whatever occurs during the night of good or evil. It is also said that it means what it veils and covers with its darkness. Another view is that it refers to what it collects of darkness. ‘Abd ibn Humayd and Ibn al-Mundhir recorded from Ibn Jubayr that he said, "And what it gathers" means "what it works in," and from this is the saying:

Sometimes you see us righteous, and at others, We stand like one who is burdened (al-wāsiq) and prepared.

It is also said that wasq means "drove," meaning what it drove to their places, such as beasts and others, or what it drove away of the light of day. From this comes the word wasīqah. It is stated in the Qāmūs that it refers to a group of camels, just as a rifqah (company) refers to a group of people; when they travel, they are driven together.