וְאִם־אֵ֣ין אַחִים֮ לְאָבִיו֒ וּנְתַתֶּ֣ם אֶת־נַחֲלָת֗וֹ לִשְׁאֵר֞וֹ הַקָּרֹ֥ב אֵלָ֛יו מִמִּשְׁפַּחְתּ֖וֹ וְיָרַ֣שׁ אֹתָ֑הּ וְֽהָ֨יְתָ֜ה לִבְנֵ֤י יִשְׂרָאֵל֙ לְחֻקַּ֣ת מִשְׁפָּ֔ט כַּאֲשֶׁ֛ר צִוָּ֥ה יְהוָ֖ה אֶת־מֹשֶֽׁה׃ (ס)
他父親若沒有弟兄，你們就要把他的產業給他家族中最近的親屬，那人就要承受這產業。這要作以色列人的法定律例，是照永恆者所吩咐摩西的。
Rashi
לשארו הקרוב אליו ממשפחתו TO HIS KIN THAT IS NEXT TO HIM OF HIS FAMILY — The term משפחה used in connection with inheritance denotes kinship only on the father’s side (Sifrei Bamidbar 134:3; Bava Batra 119b).
Ramban
AND IT SHALL BE UNTO THE CHILDREN OF ISRAEL A STATUTE OF JUDGMENT. The meaning thereof is that this judgment should be for all [future] generations, and not only for now when they inherited the Land [hence the expression “a statute, i.e., a permanent one, for all the children of Israel in all future generations”].
Rabbeinu Bahya
ונתתם את נחלתו לשארו הקרוב אליו ממשפחתו, “and you will give his inheritance to the closest (surviving) member of his family.” This verse is the source of the sages in Baba Batra 11 ruling that the husband inherits his wife. The sages use the letter ל in the word ונתתם and the letter ו in the word לשארו to construct a new word, i.e., לו, which is the basis for assigning the wife’s property to the husband upon her death. The word שארו is understood as “his wife.”