One law shall be to him that is home-born, etc. - As this is the first place that the term תורה torah or Law occurs, a term of the greatest importance in Divine revelation, and on the proper understanding of which much depends, I judge it best to give its genuine explanation once for all.
The word תורה torah comes from the root ירה yarah, which signifies to aim at, teach, point out, direct, lead, guide, make straight, or even; and from these significations of the word (and in all these senses it is used in the Bible) we may see at once the nature, properties, and design of the law of God. It is a system of Instruction in righteousness; it teaches the difference between moral good and evil; ascertains what is right and fit to be done, and what should be left undone, because improper to be performed. It continually aims at the glory of God, and the happiness of his creatures; teaches the true knowledge of the true God, and the destructive nature of sin; points out the absolute necessity of an atonement as the only means by which God can be reconciled to transgressors; and in its very significant rites and ceremonies points out the Son of God, till he should come to put away iniquity by the sacrifice of himself. It is a revelation of God's wisdom and goodness, wonderfully well calculated to direct the hearts of men into the truth, to guide their feet into the path of life, and to make straight, even, and plain that way which leads to God, and in which the soul must walk in order to arrive at eternal life. It is the fountain whence every correct notion relative to God - his perfections, providence, grace, justice, holiness, omniscience, and omnipotence, has been derived. And it has been the origin whence all the true principles of law and justice have been deduced. The pious study of it was the grand means of producing the greatest kings, the most enlightened statesmen, the most accomplished poets, and the most holy and useful men, that ever adorned the world. It is exceeded only by the Gospel of Jesus Christ, which is at once the accomplishment of its rites and predictions, and the fulfillment of its grand plan and outline. As a system of teaching or instruction, it is the most sovereign and most effectual; as by it is the knowledge of sin, and it alone is the schoolmaster, παι δαγωγος, that leads men to Christ, that they may be justified through faith. Galatians 3:24. Who can absolutely ascertain the exact quantum of obliquity in a crooked line, without the application of a straight one? And could sin, in all its twistings, windings, and varied involutions, have ever been truly ascertained, had not God given to man this perfect rule to judge by? The nations who acknowledge this revelation of God have, as far as they attained to its dictates, the wisest, purest, most equal, and most beneficial laws. The nations that do not receive it have laws at once extravagantly severe and extravagantly indulgent. The proper distinctions between moral good and evil, in such states, are not known: hence the penal sanctions are not founded on the principles of justice, weighing the exact proportion of moral turpitude; but on the most arbitrary caprices, which in many cases show the utmost indulgence to first-rate crimes, while they punish minor offenses with rigour and cruelty. What is the consequence? Just what might be reasonably expected: the will and caprice of a man being put in the place of the wisdom of God, the government is oppressive, and the people, frequently goaded to distraction, rise up in a mass and overturn it; so that the monarch, however powerful for a time, seldom lives out half his days. This was the case in Greece, in Rome, in the major part of the Asiatic governments, and is the case in all nations of the world to the present day, where the governor is despotic, and the laws not formed according to the revelation of God.
The word lex, law, among the Romans, has been derived from lego, I read; because when a law or statute was made, it was hung up in the most public places, that it might be seen, read, and known by all men, that those who were to obey the laws might not break them through ignorance, and thus incur the penalty. This was called promulgatio legis, q. provulgatio, the promulgation of the law, i.e., the laying it before the common people. Or from ligo, I bind, because the law binds men to the strict observance of its precepts. The Greeks call a law νομος nomos, from νεμω, to divide, distribute, minister to, or serve, because the law divides to all their just rights, appoints or distributes to each his proper duty, and thus serves or ministers to the welfare of the individual and the support of society. Hence where there are either no laws, or unequal and unjust ones, all is distraction, violence, rapine, oppression, anarchy, and ruin.

One (u) law shall be to him that is homeborn, and unto the stranger that sojourneth among you.
(u) They that are of the household of God, must be all joined in one faith and religion.

One law shall be to him that is homeborn,.... A proper Israelite, one that is so by descent:
and unto the stranger that sojourneth among you; that becomes a proselyte to the true religion; these were both bound by the same law, and obliged to observe the same rites and ceremonies, and partook of the same ordinances, benefits, and privileges; this was a dawn of grace to the poor Gentiles, and presignified what would be in Gospel times, when they should be fellow citizens with the saints, and of the household of God, be fellow heirs of the same body, and partakers of the promises of Christ by the Gospel, Ephesians 2:19.

One law shall be to him that is homeborn, and unto the stranger--This regulation displays the liberal spirit of the Hebrew institutions. Any foreigner might obtain admission to the privileges of the nation on complying with their sacred ordinances. In the Mosaic equally as in the Christian dispensation, privilege and duty were inseparably conjoined.

There was one law with reference to the Passover which was applicable both to the native and the foreigner: no uncircumcised man was to be allowed to eat of it.