Why does Yitzchak's blessing of Yaakov refer to Yaakov's mother's *sons*?

Question

B'reishit 27:29 reads:

Let peoples serve thee, and nations bow down to thee. Be lord over thy brethren, and let thy mother's sons bow down to thee. Cursed be every one that curseth thee, and blessed be every one that blesseth thee.

Rivka only had two sons and Yitzchak didn't have any other wives or concubines. Why does he use the plural when referring to Yaakov's mother's (other) sons?

One possibility is that he was guarding against the possibility of future children. This seems to be inconsistent with Yitzchak's health at the time he gave the blessing.

Another possibility is that by sons he means descendants, meaning Eisav and all his children, but that's unbalanced -- if Eisav's sons are his mother's sons, then so are his own sons when he has them.

Someone fluent in Hebrew told me that we should read this as mothers' sons, meaning Rivka and Sarah rather than just Rivka. This person told me that the segol in imecha is plural, but I have never seen a translation that renders it plural.

Rashi doesn't comment on this, nor do the chumashim I checked (not an exhaustive search, I know). I don't have an Ibn Ezra (I know he often comments on grammar).

Answer 1

Chizkuni says that Yitzchak is trying to include children Rivka may have if she remarries after he dies.

חזקוני בראשית פרק כז פסוק כט

בני אמך: אם היא תנשא עוד אחרי מותי.

Note: This deals with Yitzchak's health issues but assumes that Rivka's health was significantly better. If you take the Midrash's timeline, then Rivka was 37 years younger than Yitzchak and Yitzchak was 123 at the time of the blessing in question, so we do have to wonder about Rivka's capacity to give birth at the time.

Answer 2

Many say that this refers to Eisav's children (or, from Yitzchak's perspective, Yaakov's children).

Ralbag, though, doesn't have a problem with asserting that it refers to Eisav alone. (Or, of course, from Yitzchak's perspective, Yaakov alone.) Grammatically, one may refer to a single child as the "children of so-and-so". He points to "וּבְנֵי דָן חֻשִׁים" - "The children of Dan are Chushim." (Bereshis 46:23)

Also, Ralbag seems to believe that "thy mothers sons" implies people that are currently alive. Thus, if one were to say that it refers to grandchildren as well, then they would have to acknowledge either that Yitzchak knew he was speaking to Yaakov (and that Eisav had children at the time) or that Yaakov already had children to refer to (or at least Yitzchak thought he did).

An additional interpretation, suggested by Abarbanel, is that "בְּנֵי אִמֶּךָ" translates as "family of your mother", which would refer to Lavan and the rest of the descendants of Bethuel.

Answer 3

To add to the other answers: B'reishis Rabba (66:5) comments that לְאֻמִּים refers to the children of Yishma'el and the descendents of K'tura (Hagar), while "your brothers" (and seemingly also "the children of your mother") refers to Esav and his generals.

The Malbim, interpreting Yitzchak's blessing as intended for Esav, instead comments that "your brothers" refers to the children of Yishma'el and the descendents of K'tura, while "the children of your mother" refers to Ya'akov's children. The effect of the blessing was reflected, so "the children of your mother" presumably turned into a reference to Esav's children.

Answer 4

The Gur Aryeh first brings and the Chizkuni's answer (brought by @DoubleAA), and then rejects it, since Yitzchok had no right to make other children his wife may have as slaves to Yaakov.

He then answers it says "Sons of your mother" to say that just like a wife is subservient to her husband, so too will they be subservient to you (Yaakov).