Bava Batra 109A

דהכא תרתי, והכא חדא!

from the fact that here, there are two examples of the superiority of a son, designation and an ancestral field, and here, there is only one demonstration of the superiority of a brother, levirate marriage?

שדה אחוזה גופה, מהאי טעמא הוא; דקא קיימא ליה לתנא ⁠– כלום יש יבום אלא במקום שאין בן, הא יש בן אין יבום.

The Talmud answers: With regard to an ancestral field itself, the tanna establishes his ruling from this same reason: Is there levirate marriage except in a case where there is no son? In a case where there is a son, there is no levirate marriage. The determination that the redemption of the ancestral field by a son is in place of the redemption of the field by the father, whereas the redemption of the field by a brother is not, is based on the reasoning that the halakha of levirate marriage is not an indication that a brother is a closer relative than a son. Therefore, the halakha of an ancestral field cannot be regarded as a second example of the son’s superiority, as it stems from the first example, that of levirate marriage.

אימא: ״שארו״⁠ – זה האב, מלמד שהאב קודם לבת. יכול יקדים לבן? תלמוד לומר: ״הקרוב״⁠ – קרוב קרוב קודם!

The Talmud suggests an alternative derivation: Why should the father of the deceased inherit before only the brothers? Say that he should inherit before the daughter of the deceased as well by interpreting the verse as follows: “His kinsman” (Numbers 27:11), this is referring to the father, and the Torah teaches that the father precedes the daughter of the deceased in inheriting from him. One might have thought that the father of the deceased should precede the son of the deceased in inheriting from him. The verse therefore states: “Next [hakkarov] to him,” teaching that the closer [karov] one is to the deceased, the earlier one is in the order of inheritance.