התהלך לפני. לפי וגו' נתוספה ה"א על שמו ונעשה שלם ותמים למספר רמ"ח איברים שבאדם. וכן מסיק בשלהי פרק רביעי דנדרים אמר רמי בר' אבא כתיב אברם וכתיב אברהם בתחלה המליכו הקב"ה על רמ"ג איברים ולבסוף על רמ"ח ואלו הן שתי עינים ושתי אזנים וראש הגויה ובא וראה כמה גדול כח של מילה כדאיתא בפרק רביעי דנדרים ואיתמר במכילתא מה שאין קורא הכתוב אברהם ושרה בשמם אחר שנשתנה כמו שמצינו ביעקב שנקרא יעקב אחר שקראו הקב"ה ישראל מפני ששמם של אברהם ושרה הראשון לא נתעקר לגמרי אך נתוספה אות אחת של ה' על שמם ולתקן השם ומכוין שנתקן נשתקע הראשון. אבל יעקב נקרא לו שם חדש והשם הראשון לא זז ממקומו. ועוד אמרו שלכך לא נשתנה שמו של יצחק מפני שלא נקרא לו שם אלא מפי הגבורה שנא' וקראת את שמו יצחק: התהלך לפני והיה תמים, “walk before Me and become complete, free from blemish.” In order for Avraham to achieve this stature, G–d added the letter ה, a metaphor for His name, to Avraham’s name. The numerical value of the letters in Avraham’s name would then amount to 248, the number of limbs in his body. This is the conclusion arrived at in the Talmud, tractate Nedarim folio 32. According to Romi bar Abba, the reason why Abraham was first known as אברם and subsequently as אברהם is that originally G–d gave him control over 243 limbs, whereas from now on he had control over all of his 248 limbs. They are: two eyes, two ears, his torso, his head. If you want to realise how important the physical act of circumcision was, you will find this explained on folio 31 of tractate Nedarim. In the commentary known as Mechilta, it is stated that the reason why both Avraham and Sarah are never again referred to by their original names, as opposed to Yaakov, who after G–d changed his name to Yisrael is frequently still referred to by his original name Yaakov, this is because after both had their names changed, their original names had not been obliterated completely as the letters of their original names had been retained also as part of their new names. Their names had only been “improved.” Israel being a totally new name was not meant to invalidate his original name. The only reason we know this is because the Torah continues to make use of it. [The name Yaakov, given to him by outsiders, not his father, had suggested that he was somehow inferior spiritually already from birth. The angel in his nocturnal wrestling match had alluded to this. (Genesis 32,29) The Torah by continuing to use it, shows that in G–d’s eyes it never reflected upon him in a negative fashion. Ed.] The sages of the Mechilta add further that the reason why the name of the third patriarch, Yitzchok, has never been changed or amended, is that he had been named by G–d Himself, long before he had even been born. (Verse 19 in our chapter)