according to their measure,
He sends down water from the skies, and the channels flow, each according to its measure: But the torrent bears away to foam that mounts up to the surface. Even so, from that (ore) which they heat in the fire, to make ornaments or utensils therewith, there is a scum likewise. Thus doth Allah (by parables) show forth Truth and Vanity. For the scum disappears like forth cast out; while that which is for the good of mankind remains on the earth. Thus doth Allah set forth parables.
真主从云中降下雨水,一切沟壑就尽量流行。山洪载著浮渣--他们为制造首饰和器皿而熔化的金属,也有同样的浮渣。真主如此阐明真伪--至于渣滓则被冲走,至于有益于人的东西则留存在地面上。真主如此阐明许多比喻。