Avraham not Avram

Shavua Tov-

The question was asked to why the Torah tells us that Avraham must not be called Avram, but it doesn’t say that Yakov can no longer be called Yakov, after he was named, Yisrael.

It was explained in מעינה של תורה, that there was a numerical significance to the number of letters of the matriarchs and patriarchs.

The number of letters in the names, שרה רבקה רחל לאה equals thirteen, which equals, אחד, one. With the change from אברם to אברהם, the numerical value of אברהם יצחק יעקב, also equals thirteen doubled is twenty-six, equal to Hashem’s holy name of י-ה-ו-ה.

Therefore, Avraham should never be called אברהם, and יעקב should not be called ישראל, so as not to disrupt this very significant Gematria.