Why Calling Abraham by His Old Name Abram Is Forbidden

Midrash Aggadah, Genesis 17:5

"And your name shall no longer be called Abram" etc. (Genesis 17:5). And anyone who calls Abraham "Abram" transgresses a negative commandment. And if a person should whisper to you to say: the Men of the Great Assembly called him "Abram," as it says, "You are the LORD, the God who chose Abram" (Nehemiah 9:7) — say to him: rather, they were recounting the [past] deed. Do you not see that afterward they said: "and You set his name Abraham" (ibid.)?

Themes

Biblical References