Komentarz do Rodzaju 21:9

מצחק MAKING SPORT — This means worshipping idols, as it is said in reference of the Golden Calf, (Exodus 32:6) “And they rose up to make merry (לצחק).” Another explanation is that it refers to immoral conduct, just as you say in reference to Potiphar’s wife, (Genesis 39:17) “To mock (לצחק) at me.” Another explanation is that it refers to murder, as (2 Samuel 2:14) “Let the young men, I pray thee, arise and make sport (וישחקו) before us” (where they fought with and killed one another) From Sarah’s reply — “for the son of this bondwoman shall not be heir with my son״ — you may infer that he (Ishmael) was quarrelling with Isaac about the inheritance, saying, “I am the first-born and will, therefore, take a double portion”. They went into the field and he (Ishmael) took his bow and shot arrows at him (Isaac), just as you say (Proverbs 26:18-19) “As a madman who casteth firebrands, [arrows and death] and says: I am only מצחק mocking” (Genesis Rabbah 53:11).

‘METZACHEIK’ (MAKING SPORT). This refers to worshipping idols, murder and sexual immorality. He [Ishmael] quarrelled with Isaac about inheritance, saying, “I am the first-born and will take a double portion.”³²²Deuteronomy 21:17. They then went into the field, and Ishmael took his bow and shot arrows at Isaac, just as you say, As a madman who casteth firebrands, arrows and death, so is the man who deceiveth his neighbor, and saith, Am I not in sport?³²³Proverbs 26:18-19. It is from Sarah’s complaint to Abraham — for the son of this bondwoman shall not be heir, etc.³²⁴Verse 10 here. — that you learn [that they were quarrelling about the inheritance]. All this is Rashi’s language.
Here too,³²⁵See above, 19:24, where Ramban criticizes Rashi in a similar manner. Hence the word “too.” the Rabbi³⁰³Rashi. writes all the different opinions, [mentioned in the following]: “We have been taught:³²⁶Tosefta Sotah 6:6. A part thereof is mentioned in Rosh Hashanah 18b. Rabbi Shimon the son of Eleazar said, ‘There are four interpretations of Rabbi Akiba which I interpret differently, and my interpretation seems more acceptable than his. Rabbi Akiba interpreted: “And Sarah saw the son of Hagar the Egyptian, whom she had borne unto Abraham, making sport. Making sport is but a designation for idolatry, etc.” But I say Heaven forbid that such be in the house of the righteous one! Is it possible that he, of whom it was written, For I have known him, to the end that he may command his children and his household, etc.,³²⁷Above, 18:19. will have in his household idolatry, sexual immorality, and murder? Making sport mentioned here is but a designation for the inheritance. When Isaac was born and everyone rejoiced, Ishmael said to them, “Fools, I am the first-born, and I take a double portion.” From the complaint of our mother Sarah to Abraham you learn [that making sport refers to the inheritance]. And my interpretation seems more acceptable than that of Rabbi Akiba.’”
The expression of the Rabbi,³⁰³Rashi. “that Ishmael quarrelled with Isaac about the inheritance,” also does not appear correct for if so, this must have happened much later when Isaac was grown up, and Ishmael would then have been too big for his mother to carry him on her shoulder.³²⁸See Verse 14 here. Our Rabbis have also said³²⁹Yalkut Shimoni Genesis, 95: “Ishmael was seventeen years old when he left his father’s house.” Isaac was then three years of age (see Note 330). See also the note in my Hebrew commentary, p. 123. that Ishmael was seventeen years old [at the time he left his father’s house]. If so, this happened at the time when Isaac was weaned,³³⁰At the time of Isaac’s birth, Ishmael was fourteen years old. (He was thirteen at his circumcision (17:25), and a year later Isaac was born.) Now since Ishmael was seventeen when he left his father’s house, Isaac was three years old at the time, at which age he was weaned (Verse 8). [and Isaac was thus too young for Ishmael to quarrel with him about the inheritance].
Rabbi Abraham ibn Ezra said in line with the literal interpretation of Scripture that metzachek means “playing,” as is normal for every boy, and she was jealous of him because he was bigger than her son.
The correct interpretation appears to me to be that this event took place on the day that Isaac was weaned,³³¹Verse 8 here. and Sarah saw Ishmael mocking Isaac or the great feast. It is for this reason that the verse says, And Sarah saw the son of Hagar the Egyptian — rather than Ishmael — making sport. Similarly, she said, Cast out this bondwoman and her son,³²⁴Verse 10 here. for she said: “The slave who mocks his master is deserving of death or stripes, but I want only that you cast him out from before me, and that he should in no way inherit your belongings together with my son, who is the son of the mistress.” She also told Abraham to cast out his mother, as the boy was unable to leave her for he would die if he were to leave his mother.³³²See further, 44:22.

מצחק, in the meantime Ishmael was already 16 years old. Sarah did not want him to remain in the same household any longer so that he would not get ideas about sharing in the inheritance with Yitzchok.