I pause at this word in order to notice the very remarkable custom, and of the highest antiquity, observed by the patriarchs, and which it is said is observed even now by some of the descendants of Abraham after the flesh, of swearing with the hand under the thigh. Thus we find Abraham desired his servant Eliezer to swear, concerning the taking a wife for his son. (Genesis 24:2) So in like manner Jacob caused his son Joseph to swear concerning burying him not in Egypt. (Genesis 47:29 etc.) It is remarkable however, that we do not, after these striking instances, meet with a like ceremony among the Israelites, of swearing by putting the hand under the thigh, though there is smiting, in token of shame and sorrow. (See Jeremiah 31:19)
Various have been the opinions of writers as to the intention and design of it. Some have supposed that the oath was to remind the person taking it, that he and the person demanding it, were both circumcised: so that it was pledging himself by the covenant relationship between them. Others carry the matter farther, and while supposing, as the former, that the oath had respect to this fraternity and relationship in one common covenant, they add to it a reference to the person, and the expectation of the Messiah as the head and substance of the covenant; and in confirmation of this opinion they refer to that passage, Genesis 46:26 where it is said that "all the souls which cause with Jacob into Egypt, came out of his loins," or, as the margin renders it, his thigh. By which I humbly conceive is meant, as still with an eye to the covenant, an interest in the Messiah. And if this should have been the allusion, what a blessed testimony doth it hold forth of the patriarch's esteem of the salvation by Jesus Christ, and of their faith and assurance concerning it! And why may we not suppose that that early song of the royal nuptial feast of Christ with his church, which was sung by the psalmist a thousand years before Christ's incarnation, had an eye to the same, when Jesus was called upon to gird himself with his sword upon his thigh? (Psalms 65:3) We lose numberless beauties of the holy Scriptures, in our ignorance of the customs and manners of the East. But if the loins and thigh in relation to Israel's seed were the same as we have seen, Genesis 46:26, surely the girding of Christ and the clothing of Christ may without violence he considered not unsimilar. And why may not the Lord be invocated as the most mighty, with his glory and majesty to gird himself upon the seed of his loins or thigh, as God the Father be heard claring concerning the whole seed of Christ, that he shall be clothed with them? "As I live, saith the Lord," speaking to his dear Son as Mediator, "thou shalt surely clothe thee with them all as with an ornament, and bind them on thee as a bride doth?" (Isaiah 49:19) But I add no more, the Lord pardon what I have already sold if I err.