Genèse 25:6

And to the sons of the concubines of Abraham gave Abraham riches and moveable property as gifts, and sent them away from Izhak his son while he (yet) lived; and they went and dwelt eastward in the land of the orient.

BUT UNTO THE SONS OF THE CONCUBINES, THAT ABRAHAM HAD. By way of the plain meaning of Scripture, since it was said to Abraham, For in Isaac shall seed be called to thee, and in no other seed, all his consorts were concubines to him, not as wives since their children would not be among his heirs. Thus, Hagar, Sarah’s handmaid, was his concubine. However, Keturah he took unto himself as a wife for if she whom he took as a concubine had been a handmaid in his house, Scripture would not have said, And Abraham took a wife, and her name was Keturah. She is called “concubine” in Scripture — it is written in Chronicles, And the sons of Keturah, Abraham’s concubine — only for the reason that I have explained, [namely, that it had been said to Abraham, For in Isaac shall seed be called to thee]. Thus we note that Abraham took unto himself a wife from the daughters of Canaan! And should you say that she was an Egyptian or from the land of the Philistines, we may yet question why he did not send to his country and to his kindred as he did in the case of his son. But the answer is that he guarded only the seed of Isaac since it was concerning him that the Covenant was made. Furthermore, Scripture does not say, “And Abraham took a wife by the name of Keturah, the daughter of a certain Hivite or Philistine or Egyptian from a certain land,” as it says concerning Esau’s wives and similar cases. Rather, Scripture mentions only Keturah’s name because she was a Canaanite, and therefore it cut short her genealogy. Scripture does so in many places where it is not concerned with the genealogy.
Perhaps Keturah was called “concubine” because she was a handmaid who was descended from a family of slaves. And if she was a handmaid in his [Abraham’s] household and he had connection with her, Scripture would not mention her genealogy since even among the matriarchs, such as Zilpah and Bilhah, it mentions only their names.
Now Rashi wrote, “Wives are those whom a man marries with a marriage-contract; concubines have no marriage-contract, as it says in reference to the wives and concubines of David, in Tractate Sanhedrin.” But the matter is not so. A woman is called a concubine only when there is no betrothal, for a marriage-contract is only a Rabbinic ordinance. And the correct text in Tractate Sanhedrin is: “A concubine has no marriage-contract or betrothal.” However, it is possible that the sons of Noah, Note 222. too when they married wives, as is their law, by intercourse, were accustomed to write them a marriage-contract which granted dowry and gift. However, for one who wished to be a concubine to them, whom he could send away when he pleased and whose children would not be among his heirs, he would not write anything. But according to the opinion of our Rabbis that Keturah is Hagar, she was certainly a concubine [since it clearly says that Hagar was Sarah’s handmaid].

הפילגשים, Hagar and Keturah.

מתנות, gifts of large amounts of money.

קדמה אל ארץ קדם, in order that his sons could take possession of the properties he owned there.

נתן אברהם מתנות, a wording which clearly differentiates from “inheritance.” This was in order that His words (G’d’s) would be carried out, [that only Yitzchok would be his heir. Ed.]

בעודנו חי, while he had still been alive, as he did not want to rely on written instructions to be carried out after his death.

ולבני הפילגשים he had no concubines from whom he had fathered children, but the concubines in his household were concubines of male servants in his household. Their children were, of course, members of Avraham’s household who had been of service to Avraham and who had adopted his lifestyle. He gave them gifts consisting of silver and gold and livestock according to his own evaluation of who deserved how much. He most certainly gave even more valuable gifts to Ishmael and to the sons of Keturah even though the Torah does not specifically mentions this. If he gave gifts to people towards whom he had no legal obligation at all, it is obvious that people towards whom he did have such an obligation would receive their due.

מעל יצחק בנו, in order that they should not interfere with him after his death and could not quarrel with him about the inheritance.

קדמה אל ארץ קדם, he sent them off in an easterly direction. According to another interpretation, the words refer to a specific country among the countries of the East. It could well refer to Charan or Ur Casdim or both, regions which were generally loosely known as ארץ קדם, [just as we speak about the regions of the Middle East, or the Far East in our time. Ed.]

נתן אברהם מתנות, “Avraham had already given gifts.” According to the Talmud in tractate Sanhedrin folio 91, these “gifts” were the ability to utter the names of the holy name of the Lord without thereby incurring severe harm. Even nowadays, according to our author, the Moslems who are trained in theology are able to do this without coming to any harm thereby. It was difficult for Rabbi Moses to understand how Avraham a great and devout man could possibly have taught the holy Name of the Lord to wicked people. In view of this problem, Rabbi Yaakov, son of Rabbi Nachman, interpreted that line in the Talmud differently by saying that the word טומאה used in the Talmud there refers to the names of certain demons. The names of these demons are associated with the evil spirits making their homes in certain ruins, or certain cemeteries as described by the Talmud in tractate Chagigah folio 3. This is alluded to by the fact that the spelling of the word “matanot” is spelled as if it were a singular, the letter ו having been omitted. As spelled in the Torah here, the numerical value of the letters in the words נתן אברהם מתנת equals the numerical value of למדם להשביע השדים. [I have not quite figured this out. At any rate, the idea is that Avraham taught these sons of his how, when they used the names of deities when swearing an oath, they could do it in such a way as not to be guilty of violating the third of the Ten Commandments. To The reader who is interested in pursuing this further I suggest that he turns to the commentary on Sanhedrin 91 by Rabbi Reuven Margolies, page 136 מרגליות הים. Ed.]