פירוש על בראשית 26:7

לאשתו means CONCERNING HIS WIFE, just as (20:13) “Say about me (לי), He is my brother”.

AND HE SAID: SHE IS MY SISTER. They did not ask concerning the children for he would say, “They are my children from another woman.”

He said "she is my sister" and Yitzhak did not request from her that she also say this as Avraham did in a similar situation because Rivkah was exceedingly  submissive to Yitzhak as I wrote earlier at the end of Chapter 24 and for this reason did not deviate from his will in any way.

וישאלו...לאשתו, an inquiry regarding his marital status, especially the woman in whose company he had been seen. We find a parallel construction in 20,13. There are numerous such constructions, and I have dealt wit them in my commentary on 12,12.

ויאמר אחותי היא, He said: “she is my sister.” The local people did not enquire as to the maternity and paternity of the children (Esau and Yaakov.) They might have been children from a former wife, for instance.

Concerning his wife. [Rashi explains this] because [the word לאשתו in] the verse makes it sound as if they asked Rivkah, and Yitzchok answered. But this is not plausible. Perforce, [it means they asked him, concerning his wife].

וישאלו אנשי המקום לאשתו, “The inhabitants of that place enquired about the marital status of the woman accompanying him.” The reason why Rivkah was not abducted immediately, as had been Sarah when Avraham had stayed in Avimelech’s country, is that Avraham had at the time warned the Philistines by saying to them at the time: “since when is the first thing you ask a stranger about the status of the people who accompany him?” Compare Talmud Baba Metzia 92.

פן יהרגוני, “lest they kill me;” Avraham at the time had ultimately not been afraid to tell Avimelech that Sarah was his wife as it had become known how he and a few men had defeated Amrafel and his mighty armies in battle. At this point they had no reason to be afraid of Yitzchok[, seeing he had not performed any deeds of valour]. This is why he was afraid to tell the people [there that Rivkah was his wife].

כי טובת מראה היא, “for she was goodlooking;” the word מאד, “very much,” is absent here whereas it had appeared in connection with Rivkah before she had mothered twins. (Compare 24,16)