Or HaChaim on Genesis 35:10/אור החיים על בראשית ל״ה:י׳

1 לא יקרא שמך יעקב כי אם ישראל, "You will not be called Jacob but Israel, etc." We need to understand the difference between when G'd renamed Abram and when he renamed Jacob. Berachot 13 states that anyone who calls Abraham Abram nowadays violates a positive commandment, whereas it is permissible to refer to Jacob as either Jacob or Israel. Although our rabbis in the Talmud there point out that the Torah itself refers to Israel as Jacob after G'd renamed him, in view of the fact that we ignore the words לא יקרא when it comes to Jacob, why should the same rule not apply to Abraham and we should have the choice of calling him by either name?

2Perhaps the very fact that G'd limited the good news when He renamed Jacob by saying: "your name is Jacob," made this change of name qualitatively different from that of Abraham at the time. There had been no need for G'd to repeat "your name is Jacob." Who did not know this? Surely what G'd meant by this was that Jacob's permanent name would remain Jacob, but that on some occasions he would be referred to by an additional name, i.e. Israel. Why would it bother G'd that we should not refer to Abraham's original name? I believe there is a very good reason. We have to remember that names describe the nature of its bearers' souls, their essence. The Talmud Berachot 7 illustrates this point. Jacob's essence then is described by the name Jacob. Whenever he enjoyed a large measure of Holy Spirit he was referred to as "Israel." There is certainly no reason why Jacob should be deprived of his original name on account of an occasional infusion of רוח הקודש. It was quite different in the case of Abraham who retained all the letters of his original name in his expanded name also. This is why G'd commanded to call him only by his new and expanded name Abraham. By doing so one did not deny his original name at all. Perhaps Chronicles I,1 26 refers to this when it states: "Abram is Abraham." When the Torah said: "your name shall not be called, etc," the meaning is that it should not be called exclusively Jacob but also Israel. This is exactly parallel to Genesis 17,5 where Abraham's name was changed.