Parshas Vayechi

(The Segulah of Learning Zera Shimshon)

As Yaakov is on his death bed, when he is giving brachos to Efraim and Menashe, he tells his son Yosef that he knows that he holds it against him that he buried his mother, Rochel, outside of Eretz Yisroel and it was fulfillment of a direct command from Hashem.

The Ramban in Bereishis (26:5) explains why he waited this long to tell him.

Perhaps Yosef believed that the Avos kept the mitzvos of the Torah while they were in Eretz Yisroel. Because one is not allowed to marry two sisters, Rochel passed away, and was buried, outside of Eretz Yisroel.

However, the mefarshim explain that because Yaakov really intended to marry Rochel first, the bechorah was split between Yosef (his children) and Reuven, Leah's firstborn. If Yaakov could not have been married to Rochel, he would not have given her firstborn inheritance in Eretz Yisroel!

Therefore, at this point when Yaakov is giving Yosef pi shnayim, inheritance to both Menashe and Efraim, it is clear that Rochel isn't not buried in Eretz Yisroel because Yaakov could not be married to two sisters in Eretz Yisroel. (The Zera Shimshon explains that this was allowed either because it was a Divine command, or because Rochel had converted and Rochel and Leah were no longer considered sisters al pi halacha.)

Yaakov now explains to Yosef why he buried his mother outside Efrat by direct command of Hashem and for no other reason.

Source: Zera Shimshon Parshas Vayechi