Surah 13. Ar-Ra'd, Ayah 17

The interpolation of the adjective "once-dry" before "river-beds" (awdiyah) is necessitated by the absence of the definite article al before this noun. According to Zamakhshari, this indicates that only some of the river-beds are streaming with water while others, not affected by this particular rainfall, remain dry. It is to be borne in mind that the term wad (or wadi in popular parlance) denotes, primarily, a "water-course" or "river-bed" which is normally dry and carries water only after copious rainfalls; it is only by extension that this term is sometimes applied to an actual river.

Sc., "while the water beneath remains clear".

This verse is full of parables. (1) It is Allah Who sends rain and sends it to all. See how it flows in different channels according to their capacities. Some are sluggish-, some have a swift current. Some form great rivers and irrigate wide tracts of country; some are clear crystal streams, perhaps in hilly tracts, with beds of clean pebbles which you can see through the water. Some produce delicious edible fish; and some are infested by crocodiles or injurious monsters. And there are degrees and degrees among brooks, streams, lakes, rivers, and seas. So with the rain of Allah's mercy and the knowledge and wisdom and guidance which He sends. All can receive it. Different ones will respond according to their capacities. (2) In the physical world, water is pure and beneficial. But froth and scum will gather according to local conditions. As the floods will carry off the scum and purify the water, so will the flood of Allah's spiritual mercy carry away our spiritual scum and purify the water. (3) The froth may make a greater show on the surface, but it will not last. So will there be frothy knowledge, which will disappear, but Allah's Truth will endure.

In continuation of the last note, the fourth parable is that of metal ores: (4) the ore is full of baser admixture, but the fire will separate the gold from the dross for ornaments, or (5) some metal of household utility, with which you make every-day utensils, which the fire will separate from admixtures which you do not want. So the fire of Allah's test, either by adversity or by affluence, will search out the true metal in us and reject the dross. It will show us what is valuable or what is useful, all sorts of scum and vanity which we collect and miscall knowledge.