This is the thing which the LORD hath commanded, Gather of it every man according to his eating, an omer for every man, according to the number of your persons; take ye every man for them which are in his tents. An omer for every man - I shall here once for all give a short account of the measures of capacity among the Hebrews.
Omer, עמר from the root amar, to press, squeeze, collect, and bind together; hence a sheaf of corn - a multitude of stalks pressed together. It is supposed that the omer, which contained about three quarts English, had its name from this circumstance; that it was the most contracted or the smallest measure of things dry known to the ancient Hebrews; for the קב kab, which was less, was not known till the reign of Jehoram, king of Israel, 2 Kings 6:25 - Parkhurst.
The Ephah, אפה or איפה eiphah, from אפה aphah, to bake, because this was probably the quantity which was baked at one time. According to Bishop Cumberland the ephah contained seven gallons, two quarts, and about half a pint, wine measure; and as the omer was the tenth part of the ephah, Exodus 16:36, it must have contained about six pints English.
The Kab, קב is said to have contained about the sixth part of a seah, or three pints and one third English.
The Homer, חמר chomer, mentioned Leviticus 27:16, was quite a different measure from that above, and is a different word in the Hebrew. The chomer was the largest measure of capacity among the Hebrews, being equal to ten baths or ephahs, amounting to about seventy-five gallons, three pints, English. See Ezekiel 45:11, Ezekiel 45:13, Ezekiel 45:14. Goodwin supposes that this measure derived its name from חמר chamor, an ass, being the ordinary load of that animal.
The Bath, בת, was the largest measure of capacity next to the homer, of which it was the tenth part. It was the same as the ephah, and consequently contained about seven gallons, two quarts, and half a pint, and is always used in Scripture as a measure of liquids.
The Seah, סאה, was a measure of capacity for things dry, equal to about two gallons and a half English. See 2 Kings 7:1, 2 Kings 7:16, 2 Kings 7:18.
The Hin, הין, according to Bishop Cumberland, was the one-sixth part of an ephah, and contained a little more than one gallon and two pints. See Exodus 29:40.
The Log, לג, was the smallest measure of capacity for liquids among the Hebrews: it contained about three quarters of a pint. See Leviticus 14:10, Leviticus 14:12.
Take ye - for them which are in his tents - Some might have been confined in their tents through sickness or infirmity, and charity required that those who were in health should gather a portion for them. For though the psalmist says, Psalms 105:37, There was not one feeble person among their tribes, this must refer principally to their healthy state when brought out of Egypt; for it appears that there were many infirm among them when attacked by the Amalekites. See Clarke's note on Exodus 17:8.