Eruvin 51A

אמר רבא: והוא דכי רהיט לעיקרו מטי. אמר ליה אביי: והא ״חשכה לו״ קתני!

Rava said: This halakha applies only in a case where, were he to run to the trunk of the tree he could reach it before the onset of Shabbat. Abaye said to him: But doesn’t the Mishnah state: And it grew dark while he was traveling, indicating that he is farther away than that?

״חשכה״⁠ — לביתו, אבל לעיקרו של אילן מצי אזיל. איכא דאמרי אמר רבא: חשכה לו כי מסגי קלי קלי, אבל רהיט ⁠— מטי.

The Talmud answers: The Mishnah means that it grew dark while he was traveling so that he can no longer return to his house before nightfall; however, he is able to go to the trunk of the tree before Shabbat. Some state a different version of the previous statement. Rava said: The Mishnah means that it grew dark while he was traveling, so that were he to walk very slowly he could not reach his house; however, if he runs, he can still arrive before Shabbat.

רבה ורב יוסף הוו קא אזלי באורחא. אמר ליה רבה לרב יוסף: תהא שביתתנו תותי דיקלא דסביל אחוה. ואמרי לה: תותי דיקלא דפריק מריה מכרגא.

Rabba and Rav Yosef were going together along the way. Rabba said to Rav Yosef: Our residence will be beneath the palm that carries its brother, the one with another palm tree leaning on it. And some say he said to him: Our residence will be beneath the palm that spared its owner from the land tax [karga], the palm which yielded enough dates for its owner to pay his entire land tax.

ידע ליה מר? אמר ליה: לא ידענא ליה. אמר ליה: סמוך עלי, דתניא, רבי יוסי אומר: אם היו שנים, אחד מכיר ואחד שאינו מכיר ⁠— זה שאינו מכיר מוסר שביתתו למכיר, זה שמכיר אומר: תהא ״שביתתנו במקום פלוני״.

Rabba asked: Does the Master know of that tree? Rav Yosef said to him: No, I do not know of it. He said to him: Then rely on me, as it was taught in a baraita that R' Yosei says: If two people were walking together, one of whom is familiar with a particular location in the distance, and one is not familiar with it, the one who is not familiar with it entrusts his right to designate his residence to the one who is familiar with it, and the one who is familiar with it says: My residence is in such-and-such place.