Mitzvot in Israel

Shavua Tov. Rabbeinu Bechaye asks an interesting question regarding today’s Parsha. Yitzchak is told by Hashem that Avraham kept all of the Mitzvot down to the last detail.

The Gemara says that Avraham even kept the laws of Eiruv as he knew the entire Torah intuitively. If it’s true that the Patriarchs kept the entire Torah, how did Yakov marry two sisters and how did עמרם marry his aunt, יוכבד?

The answer by Rabbeinu Bechaye is that these apparent violations took place outside of Eretz Yisrael. But in Israel, they did keep all of the Mitzvot. Another proof that the Mitzvot in Chutz L’aretz are all for practice to get it right in Israel.