The Children of Keturah

Once when Rav Shimon Sofer, the Rav of Krakow, was in Warsaw, some rabannim and scholars met with him. Among the crowd was a certain rav who said over many new and interesting Torah concepts, but Rav Sofer understood that although his words sounded very brilliant they were not really true.
Rav Sofer said to his visitor, “We find in the the gemara in Zevachim 62 that the nephews of Rabbi Tarfon were sitting in front of their uncle. Rashi explains that they remained silent. But how could this be? This must mean that they were speaking in learning, but Rashi calls it silence since their words were not the absolute truth. Rabbi Tarfon misquoted the verse, 'ויוסף אברהם ויקח אשה ושמה...'—‘And Avraham went on and took for a wife...’ However, instead of saying Keturah he said Yochni. His nephews immediately corrected him, ‘She was called Keturah!’
“‘You are like the Bnei Keutrah,’ Rabbi Tarfon answered back. Could it be that the great Rabbi Tarfon accidentally misquoted a verse? It is clear that he did so intentionally so that his nephews should break off speaking Torah not directed towards the truth, by correcting him that her name was actually Keturah, which is one hundred percent true. In this manner he taught them that truth is better than the sharpest vertlach that are not founded on absolute truth. It is better not to have lived if all one is occupied with is essentially false Torah.”
The Pnei Menachem, zt”l, explains differently, “He called them Bnei Keturah since he saw that they were immersed in the wakeful slumber of one who is completely focused on material matters. He therefore arranged to call them Bnei Keturah to teach them that they should not be like the children of Hagar. Rather they should act like the children of Sorah who make good use of their time since they value every minute and every hour of each day.”