Parashas Bamidbar
שְׂא֗וּ אֶת־רֹאשׁ֙ כׇּל־עֲדַ֣ת בְּנֵֽי־יִשְׂרָאֵ֔ל לְמִשְׁפְּחֹתָ֖ם לְבֵ֣ית אֲבֹתָ֑ם בְּמִסְפַּ֣ר שֵׁמ֔וֹת כׇּל־זָכָ֖ר לְגֻלְגְּלֹתָֽם׃
Take a census of the whole Israelite communityawhole Israelite community Or those eligible to be fighters on the community’s behalf. by the clans of its ancestral houses,bits ancestral houses I.e., its tribes. listing the names, every male, head by head.
Torah Temimah points to TT / Yevamos / related (verified).
למשפחתם לבית אבתם — מכאן דמשפחת אב קרויה משפחה, משפחת אם אינה קרויה משפחה.
English: “By their families, by their fathers’ houses” — from here [we learn] that the family of the father is called a family; the family of the mother is not called a family.
Custom
Chazal derive that “family” for these purposes follows the father’s house, not the mother’s.