5 And the servant said unto him, Peradventure the woman will not be willing to follow me unto this land: must I needs bring thy son again unto the land from whence thou camest? 6 And Abraham said unto him, Beware thou that thou bring not my son thither again. 7 The Lord God of heaven, which took me from my father’s house, and from the land of my kindred, and which spake unto me, and that sware unto me, saying, Unto thy seed will I give this land; he shall send his angel before thee, and thou shalt take a wife unto my son from thence. 8 And if the woman will not be willing to follow thee, then thou shalt be clear from this my oath: only bring not my son thither again. 9 And the servant put his hand under the thigh of Abraham his master, and sware to him concerning that matter.
There is a natural hesitation in us when asked to make a pledge that depends on elements not under our control. What if we simply can’t fulfill that promise? Of course it is good to have faith in the face of the unknown, but faith is a muscle that is strengthened over time, and sometimes we lack the faith that the moment requires.
To the servant’s credit, he tries to find a solution to help bolster his commitment. He asks if he should just bring Isaac back to the land of Ur of the Chaldees if he fails in the first attempt to find a wife. He is ready to commit to try and to keep trying, he’s just not so sure on guaranteeing success.
Abraham absolutely does not want his son brought back to that land, so he turns down the servant’s idea, but then he does two things to help inspire and alleviate his servant. The first is that he encourages the man by saying that this is the will of God. God was the one who made a solemn covenant to Abraham that a righteous nation would be raised through Isaac, so God is actively interested in Isaac finding a righteous companion, and He will prepare the way for the servant’s success. The servant has nothing to fear.
However, in the case that the servant does still fear, Abraham then tells him that if he is unable to find a wife for Isaac then he is free of any obligation. That would, of course, leave Abraham without a solution to his problem, but Abraham isn’t concerned about that. Unlike the servant, he has sufficient faith in this plan that he does not require a backup. Thus Abraham is extending his own faith to cover the lack of his servant’s in this instance.