A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
exo 23:1LAWS CONCERNING SLANDER, &c. (Exo. 23:1-33)
put not thine hand--join not hands.
exo 23:2decline--depart, deviate from the straight path of rectitude.
exo 23:3countenance--adorn, embellish--thou shalt not varnish the cause even of a poor man to give it a better coloring than it merits.
exo 23:10six years thou shalt sow thy land--intermitting the cultivation of the land every seventh year. But it appears that even then there was a spontaneous produce which the poor were permitted freely to gather for their use, and the beasts driven out fed on the remainder, the owners of fields not being allowed to reap or collect the fruits of the vineyard or oliveyard during the course of this sabbatical year. This was a regulation subservient to many excellent purposes; for, besides inculcating the general lesson of dependence on Providence, and of confidence in His faithfulness to His promise respecting the triple increase on the sixth year (Lev 25:20-21), it gave the Israelites a practical proof that they held their properties of the Lord as His tenants, and must conform to His rules on pain of forfeiting the lease of them.
exo 23:12Six days thou shalt do thy work, and on the seventh day thou shalt rest--This law is repeated [Exo 20:9] lest any might suppose there was a relaxation of its observance during the sabbatical year.
exo 23:13make no mention of the name of other gods, &c.--that is, in common conversation, for a familiar use of them would tend to lessen horror of idolatry.
exo 23:14Three times . . . keep a feast . . . in the year--This was the institution of the great religious festivals--"The feast of unleavened bread," or the passover--"the feast of harvest," or pentecost--"the feast of ingathering," or the feast of tabernacles, which was a memorial of the dwelling in booths in the wilderness, and which was observed in the seventh month (Exo 12:2). All the males were enjoined to repair to the tabernacle and afterwards the temple, and the women frequently went. The institution of this national custom was of the greatest importance in many ways: by keeping up a national sense of religion and a public uniformity in worship, by creating a bond of unity, and also by promoting internal commerce among the people. Though the absence of all the males at these three festivals left the country defenseless, a special promise was given of divine protection, and no incursion of enemies was ever permitted to happen on those occasions.
exo 23:19Thou shalt not seethe a kid in his mother's milk--A prohibition against imitating the superstitious rites of the idolaters in Egypt, who, at the end of their harvest, seethed a kid in its mother's milk and sprinkled the broth as a magical charm on their gardens and fields, to render them more productive the following season. [See on Deu 14:21].
exo 23:20Behold, I send an Angel before thee, to keep thee in the way--The communication of these laws, made to Moses and by him rehearsed to the people, was concluded by the addition of many animating promises, intermingled with several solemn warnings that lapses into sin and idolatry would not be tolerated or passed with impunity.
exo 23:21my name is in him--This angel is frequently called Jehovah and Elohim, that is, God.
exo 23:28I will send hornets before thee, &c. (See on Jos 24:12) --Some instrument of divine judgment, but variously interpreted: as hornets in a literal sense [BOCHART]; as a pestilential disease [ROSENMULLER]; as a terror of the Lord, an extraordinary dejection [JUNIUS].
exo 23:29I will not drive . . . out . . . in one year; lest the land become desolate--Many reasons recommend a gradual extirpation of the former inhabitants of Canaan. But only one is here specified--the danger lest, in the unoccupied grounds, wild beasts should inconveniently multiply; a clear proof that the promised land was more than sufficient to contain the actual population of the Israelites.