And Abraham said unto his eldest servant of his house, that ruled over all that he had, {a} Put, I pray thee, thy hand under my thigh:

(a) Which ceremony declared, the servants obedience towards his master, and the master's power over the servant.

Wesley's Notes

24:2 His eldest servant - Probably Eliezer of Damascus, one whose conduct and affection he had had long experience of: he trusted him with this great affair, and not Isaac himself, because he would not have Isaac go at all into that country, but marry thither by proxy; and no proxy so fit as the steward of his house. This matter is settled between the master and the servant with a great deal of care and solemnity. The servant is bound by an oath to do his utmost to get a wife for Isaac among his relations, Ge 24:3,4. Abraham swears him to it, both for his own satisfaction, and for the engagement of his servant to all possible care and diligence. Thus God swears his servants to their work, that, having sworn, they may perform it. Swearing being an ordinance, not peculiar to the church, but common to mankind, is to be performed by such signs as are the common usages of our country.

Jamieson-Fausset-Brown Bible Commentary

2. said unto his eldest servant-Abraham being too old, and as the heir of the promise not being at liberty to make even a temporary visit to his native land, was obliged to intrust this delicate mission to Eliezer, whom, although putting entire confidence in him, he on this occasion bound by a solemn oath. A pastoral chief in the present day would follow the same course if he could not go himself.

Matthew Henry's Concise Commentary

24:1-9 The effect of good example, good teaching, and the worship of God in a family, will generally appear in the piety, faithfulness, prudence, and affection of the servants. To live in such families, or to have such servants, both are blessings from God which should be highly valued, and thankfully acknowledged. But no concern in life is of greater importance to ourselves, to others, or to the church of God, than marriage. It therefore ought always to be undertaken with much care and prudence, especially with reference to the will of God, and with prayer for his direction and blessing. Where good parents are not consulted and regarded, the blessing of God cannot be expected. Parents, in disposing of their children, should carefully consult the welfare of their souls, and their furtherance in the way to heaven. Observe the charge Abraham gave to a good servant, one whose conduct, faithfulness, and affection, to him and his family, he had long known. Observe also, that Abraham remembers that God had wonderfully brought him out of the land of his birth, by the call of his grace; and therefore doubts not but He will prosper his care, not to bring his son thither again. God will cause that to end in our comfort, in which we sincerely aim at his glory.