Yitzchak sowed [crops] in that land [which was not as fertile as the main part of the Land of Israel], and he found [even] in that year [which was a bad one for crops, that the land yielded] a hundred times [more than average]—and G‑d blessed him.

-- Breshis 26:12

Classic Questions

How did they know that the land yielded a hundred times more than average? (v. 12)

Rashi: They had estimated how much the land was fit to produce, and it produced one hundred measures for each measure that they had estimated. Our Rabbis said that the purpose of this estimate was for separating ma'aser (tithes).

Midrash: There is a principle that G‑d's blessing does not rest on something which is weighed, measured or counted. However, in the case of measuring for a mitzvah, this principle does not apply. Therefore, Yitzchak measured the field for the purposes of tithing.

Gur Aryeh: We see from the Midrash that Rashi's two comments are one single explanation: Yitzchak measured the field specifically for a mitzvah, and therefore he received G‑d's blessings.

The Rebbe's Teachings

Yitzchak's Hundred-Fold Blessing (v. 12)

After explaining that Yitzchak compared the yield of his land with that year's expected yield, Rashi continues with the explanation of "our rabbis" that "the purpose of this estimate was for separating ma'aser."

This raises the question: What is lacking with Rashi's first explanation that led him to bring the interpretation of the rabbis?

Gur Aryeh, following the Midrash, explains that Rashi was troubled as to why Yitzchak would measure his field knowing that "G‑d's blessing does not rest on something which is weighed, measured or counted."

However, at the literal level of Torah interpretation, there is no indication that this was Yitzchak's concern. Therefore, it is difficult to accept that this was Rashi's problem.

So what forced Rashi to conclude that Yitzchak measured the field for the purposes of separating ma'aser, and not simply because he wanted to estimate its approximate yield at the time of purchase, to see if he was being charged the correct price?

The Explanation

A key distinction between Rashi's two explanations concerns the time at which the estimate was made. According to Rashi's first interpretation—that Yitzchak measured the field to estimate how much it would yield—he obviously measured it before the crops had grown, presumably when purchasing the field, to assess its value. However, according to Rashi's second interpretation (from "our Rabbis"), that he measured it for the purposes of separating ma'aser, it turns out that Yitzchak would have measured the crops after they had fully grown, since ma'aser is one tenth of the actual yield.

Obviously (according to both interpretations) the blessing of finding one-hundredfold must have occurred after Yitzchak had made his calculations, otherwise he would have no way of knowing that the magnitude of the increase was one hundredfold.

Thus, according to Rashi's second interpretation (that he measured for the purposes of separating ma'aser), the one-hundredfold increase would have occurred after Yitzchak measured them. Thus, a great miracle must have occurred, that the crops increased a hundredfold after they had fully grown!

According to the first interpretation, however, that Yitzchak estimated how much the field would produce in advance, the hundredfold increase could have occurred more naturally, throughout the entire period of the crops' growth. Thus, Rashi placed this interpretation first, as it is more acceptable at the literal level.

Nevertheless, there is a problem with the first interpretation which led Rashi to add the explanation of the Rabbis:

According to Rashi, the land where Yitzchak was situated was infertile, and that year was a famine (Rashi on the beginning of v. 12). Though it would have been quite surprising for Yitzchak to find one hundred times more than the average yield for that year, even that would not have made him prosperous, since the average for that year was so pitiful. The Torah, however, appears to indicate that Yitzchak did become wealthy from the harvest, as the next verse continues, "The man [Yitzchak] became prosperous."

Therefore, in order to explain why he became prosperous, Rashi brought the second explanation, that Yitzchak's yield multiplied miraculously one hundred times after it had already grown. This yield would have been much greater, since we are speaking here of 100 times Yitzchak's real yield, rather than 100 times the estimated average local yield. And surely, Yitzchak—being a tzadik—would have been blessed by G‑d to reap well above the average yield for that year.

(Based on Likutei Sichos vol. 5, p. 121ff; Sichas Shabbos Parshas Toldos 5727)