He destroyed their vines with hail - Margin, killed. See Exodus 9:22-26. In the account in Exodus the hail is said to have smitten man and beast, the herb, and the tree of the field. In the psalm only one thing is mentioned, perhaps denoting the ruin by what would be particularly felt in Palestine, where the culture of the grape was so common and so important.
And their sycamore trees with frost - The sycamore is mentioned particularly as giving poetic beauty to the passage. Of the sycamore tree, Dr. Thomson remarks ("land and the Book," vol. i. p. 25), "It is a tender tree, flourishes immensely in sandy plains and warm vales, but cannot bear the hard, cold mountain. A sharp frost will kill them; and this agrees with the fact that they were killed by it in Egypt. Among the wonders performed in the field of Zoan, David says, 'He destroyed their vines with hail, and their sycamores with frost.' Certainly, a frost keen enough to kill the sycamore would be one of the greatest 'wonders' that could happen at the present day in this same field of Zoan." The word rendered "frost" - חנמל chănâmâl - occurs nowhere else. It is parallel with the word hail in the other member of the sentence, and denotes something that would be destructive to trees. The Septuagint, the Vulgate, and the Arabic render it frost. Gesenius renders it ants.

He destroyed their vines with hail - Though the vine was never plentiful in Egypt, yet they have some; and the wine made in that country is among the most delicious. The leaf of the vine is often used by the Egyptians of the present day for wrapping up their mince-meat, which they lay leaf upon leaf, season it after their fashion, and so cook it, making it a most exquisite sort of food, according to Mr. Maillet.
And their sycamore-trees - This tree was very useful to the ancient Egyptians, as all their coffins are made of this wood; and to the modern, as their barques are made of it. Besides, it produces a kind of fig, on which the common people in general live; and Mr. Norden observes that "they think themselves well regaled when they have a piece of bread, a couple of sycamore figs, and a pitcher of water from the Nile." The loss therefore of their vines and sycamore-trees must have been very distressing to the Egyptians.

He destroyed their vines with hail,.... Or "killed" (k) them; for there is a vegetative life in plants: this was the seventh plague of Egypt, attended with thunder and lightning, and was very terrible to Pharaoh, Exodus 9:23, with this compare Revelation 16:21,
and their sycamore trees with frost: sycamore trees, according to Kimchi, were a sort of wild figs, and these with the vines are only mentioned; though the plague of hail destroyed all sorts of trees; because there were many of these in Egypt, and are put for all others; and who also observes, that the word rendered "frost", which is only used in this place, signifies a kind of hail; and so Aben Ezra interprets it of great hailstones which beat off the fruit of the sycamore trees: but R. Saadiah Gaon explains it by the Arabic word "Al-sakia", which signifies a strong frost which breaks the buds of trees, and dries up their moisture. Jarchi will have it to be, according to the Midrash, a kind of locust, which comes and sits and cuts off the green of the trees and grass, and eats it. Aben Ezra makes mention of this sense, but rejects it.
(k) "occidit", Pagninus, Montanus, Musculus, Junius & Tremellius, Piscator; "interfecit", Gejerus.

The additional effects of the storm here mentioned (compare Exodus 9:23-34) are consistent with Moses' account.

Sycamore - trees - Under these and the vines, all other trees are comprehended. This hail and frost destroyed the fruit of the trees, and sometimes the trees themselves.