Commentary for Genesis 17:19

אבל VERILY — This word implies confirmation of a statement, just as (Genesis 42:21) “Verily (אבל) we are guilty”, and (2 Kings 4:14) “Verily (אבל) she has no son”.

‘AVAL’ SARAH THY WIFE. This is like the verse, “Aval” she has no son,⁴⁵⁷II Kings 4:14. the word aval meaning “only.” He thus said: “Only the son of whom I informed you, your wife Sarah will give birth to, and with him will I establish My covenant forever and with his seed after him; and Ishmael I will bless by making his children numerous, but this will not be because of My covenant with him.”

Sarah will bear you a son. In verse 16 God did not mention that Sarah would actually bear a son, so Avraham thought that perhaps she would adopt one.

ויאמר אלוקים אבל שדה אשתך יולדת לך בן. G'd said: "But your wife Sarah will bear a son for you." Why did G'd add the word "but?"

ויאמר ... אבל שרה אשתך, Ishmael will not remain your only son, but also Sarah will bear a son for you and you are to call his name Yitzchok, as a reminder that you laughed happily when you heard Me inform you of this.

אבל שרה אשתך, “but your wife Sarah, etc.” The word אבל in this instance means the same as the word everywhere else, i.e. We find a parallel for this in Kings II 4,14 אבל בן אי לו, “only (except) she has no son.”

וקראת את שמו יצחק, “and you will name him ‘Yitzchak.’” Yitzchak was given this name by G-d. This is why we never find that he was given another name such as his father or his son Yaakov who was given the additional name Yisrael. Both Avram’s name and Yaakov’s name had been given them by their respective fathers and not by G-d Himself. I have found a remark confirming this in the Jerusalem Talmud at the end of the first chapter of Berachot. The rhetorical question posed there is: “Why was Yitzchak’s name never amended whereas the names of Avraham and Yaakov were amended?” Answer: ‘’because the latter’s name was G-d-given, whereas the names of the former were given to them by their respective fathers.” The Talmud quotes our verse here as the source for claiming that G-d commanded Avraham to call the name of his son Yitzchak. You might retort that we also encounter Yitzchak’s name spelled with the letter ש instead of the letter צ in Psalms 108,9, and that this is as much of a change as spelling אברהם without the letter ה. Actually, the word ישחק is not a new name at all. The prophet wanted to draw attention to the element fire which was one of the basic elements in Yitzchak’s character as we know from the ספר יצירה where the author writes (edition of Gaon from Vilna chapter 6 Mishnah 2) “there are three אמות which are known as אמ'ש “which are air, water and fire.” Whereas the מ is silent, static, the א is constantly in motion so that the letter ש is an allusion to the great fire, a characteristic of Yitzchak. [Fire is perceived as vanquishing water, rising even during the process of water “extinguishing” fire and remaining behind on the ground. (abbreviated quote from the comment of the Gaon from Vilna). Ed.]
Another reason why Avram’s name had to be changed whereas Yitzchak’s name did not need to be changed: G-d had given Avraham an additional destiny, i.e. to become a founder of many nations. This had to be reflected in his name being changed. Similarly Yaakov. His additional name Yisrael was in recognition of his having successfully contended with opposing celestial forces as attested to by the angel who struggled with him (Genesis 32,29). Yitzchak had not had similar experiences so that these did not require any changes or additions to his name. He had remained throughout his life on holy soil in the Holy Land.

Based on the laughter. Some say, based on the ten trials. Both explanations are needed. For if he was so named because of laughter [alone], his name should be צחוק. Why is there a י? Perforce, it is because of the ten trials. And this entails saying that ח is for circumcision performed on the 8th day, and צ and ק are for Sarah’s 90 years and Avraham’s 100. But this explanation alone is insufficient, for it says clearly (21:6): “God has given me laughter,” indicating he was so named because of laughter. (Gur Aryeh)

אבל ,אבל: trauern, אפל: dunkel, אול, wovon אולַי, zweifeln, alle drei drücken einen getrübten, verdunkelten Zustand aus, אפל physisch, אבל im Gemüte, -tlähreV nerhi dnu negniD ned nov red ליִוְֶא hcua tmmok לוא nov .etsieG mi לוא nissen nur eine unklare, schwankende Vorstellung hat. צְַבָל tritt überall einer im Ge- müte des Hörenden vorhandenen Gedankenreihe entgegen, sie beschränkend: aber, jedoch, doch! (Vergl. S. 80). So auch hier, in der Ausdehnung, wie Abraham die Zukunft Ismaels wünschte, wird sie sich nicht realisieren.

והקימותי את בריתי אתו, “I will maintain My covenant (the promise contained therein) with him.” G-d means that Yitzchok will be the first person to be circumcised on the eighth day of his life.

וקראת את שמו יצחק AND THOU SHALL CALL HIS NAME ISAAC — with reference to his laughter. Some say the name has reference to the ten (י) trials, the ninety (צ) years of Sarah’s age, the eight (ח) days of the circumcision and the hundred (ק) years of Abraham’s age (Genesis Rabbah 53:7).

לברית עולם לזרעו אחריו, the covenant I made with you will be perpetuated through Yitzchok's seed.

G'd may have wanted to explain to Abraham that if the gift of a son was something intended only for Abraham, it would suffice to grant his prayer and assist Ishmael to become worthy. However, there was another person to be considered, his wife Sarah. Inasmuch as Sarah was destined to bear a son, he, Abraham, had no right to waive the gift of a son by Sarah in order for Ishmael to grow up worthy of his father. The Torah was very particular using the word לך, "for you," in connection with the son Sarah would bear. She would bear this son in answer to her prayer.

והקמתי את בריתי AND I WILL ESTABLISH MY COVENANT WITH HIM — Why is this stated? Is it not already written (Genesis 17:9) “as for thee, thou shalt keep My Covenant, thou and thy seed etc.”? But since is said, (Genesis 17:7) and I will establish My Covenant between Me and thee and thy seed after thee in their generations”, it might be inferred that the children of Ishmael and the children of Keturah (who are all descendants of Abraham) are included in this promise of the establishment of the Covenant, therefore it states here (Genesis 17:19) “And I will establish My Covenant with him (Isaac), not with the others” (cf. Sanhedrin 59b). If so, why is there a repetition of the statement that the covenant will be established with Isaac in the words (Genesis 17:21) ואת בריתי אקים את יצחק “but My Covenant will I establish with Isaac”? But it is repeated in order to add the words אשר תלד so as to teach that he was holy from his birth (Shabbat 137b). Another explanation of why 5:21 is repeated is: R. Aba said, “from here Scripture draws a logical conclusion regarding the son of the Mistress (Sarah) from what is said regarding the son of the handmaid (Hagar): It is written (Genesis 17:20) “Behold I have blessed him and will make him fruitful”, and this refers to Ishmael: Surely then, it follows logically that “I must establish my covenant (of blessing) with Isaac also!” (Genesis Rabbah 47:5).

It is also possible that the Torah here hinted at G'd's displeasure that Abraham was satisfied with Ishmael, someone who contained residual poisonous material from the original serpent. Had it not been for Abraham's prayer regarding the future of Ishmael, his son Isaac might not have originated in what kabbalists know as the סטרא דנוקבא, an emanation on the left and female side of the emanations. Had Isaac originated in the other side of the emanations he might never have fathered an Esau. This matter had ramifications at the time of the עקדה, when Isaac received the soul who would bear children for him, i.e. the moment at which Rebeccah his life-partner was born.

את בריתי [I WILL ESTABLISH] MY COVENANT — The Covenant of circumcision shall be transmitted only to the descendants of Isaac.