C. F. Keil and Franz Delitzsch on Proverbs 25:13

Pro 25:13

The following comparative tristich refers to faithful service rendered by words:

Like the coolness of snow on a harvest day

Is a faithful messenger to them that send him:

He refresheth the soul of his master.

The coolness (צנּה from צנן, צנן, to be cool) of snow is not that of a fall of snow, which in the time of harvest would be a calamity, but of drink cooled with snow, which was brought from Lebanon or elsewhere, from the clefts of the rocks; the peasants of Damascus store up the winter’s snow in a cleft of the mountains, and convey it in the warm months to Damascus and the coast towns. Such a refreshment is a faithful messenger (vid., regarding ציר, Pro 13:17, here following קציר as a kind of echo) to them that send him (vid., regarding this plur. at Pro 10:26, cf. Pro 22:21); he refreshes, namely (ו explicativum, as e.g., Eze 18:19, etenim filius, like the ו et quidem, Mal 1:11, different from the ו of conditional clause Pro 23:3), the soul of his master; for the answer which he brings to his master refreshes him, as does a drink of snow-cooled water on a hot harvest day.