Yevamos 122a: When Rabban Gamliel heard this, he recalled that men were once killed at Tel Arza, and Rabban Gamliel had permitted their wives to remarry based on the testimony of one witness.
The Seder Hadoros learns that this was Rabban Gamliel of Yavneh remembering a story about his grandfather Rabban Gamliel Hazakein. Rav Ovadiah Yosef (Yabia Omer v. 5 YD 21) proves from this that in Talmudic times, a grandson was named after a living grandfather, as is the Sephardi custom today.
But Ashkenazi custom, brought in Sefer Chassidim, Section 460, is not to name a baby after a living relative, because people are superstitious about it, and Chazal’s rule (Pesachim 110b) is that when it comes to demons, witchcraft and the like, if someone is particular about it, he is affected by it.
יבמות קכב ע”א: מתוך הדבר נזכר ר״ג שנהרגו הרוגים בתל ארזא, והשיא ר״ג נשותיהן על פי עד אחד,
שו”ת יביע אומר ח”ה חיו”ד כא: וכן הוא בסדר הדורות (ערך רבן גמליאל דיבנה אות ב’) כתב דרשב”ג שהיה מעשרה הרוגי מלכות קרא לבנו רבן גמליאל (דיבנה) ע”ש אביו רבן גמליאל בחיים חיותו.
ספר חסידים תנט-תס: כל הניחושים כנגד המקפידים וכתיב כי קפדה בא ובקשו שלום ואין (יחזקאל ז,כה). מכאן כל דקפיד קפדו בהדיה (פסחים קי ע”ב). ומתוך שאין אדם יכל להזהר בהקפדות נכשל. נכרים שקוראים לבניהם בשם אביהם אין בכך כלום והיהודים מקפידים על כך ויש מקומות שאין קורין אחר שמות החיים אלא אחר שכבר מתו.
Sometimes, quarrelling in a marriage can be a good thing. There was once an Ashkenazi couple that had a newborn baby boy, and they disagreed on what to name him. Both husband and wife had fathers who had recently passed away. The husband wanted to name the baby Avraham, after the wife’s father, while the wife wanted to name him Moshe after the husband’s father! They went to ask a rav, who ruled in favor of the husband.
“But,” said the wife, “my grandfather is still alive and his name is Avraham Yitzchak.” She called him on the phone. The grandfather declared, “I would have no problem if the baby is named Avraham. I come from several generations of rabbis, and the family always gave names even if they happened to be the same as the names of living people.”
The rav consulted Rav Elyashiv, who responded, “Even though he may not have a problem, since most Ashkenazi Jews are makpid, you should not give him that name. One must not trifle with a Jewish custom.”
Source: Tuvcha Yabiu, Parshas Bereishis, quoted in Veyikarei Shmo Beyisroel p. 458
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