一切經音義 27.145

27.145

姓（說文人所生也古之神人聖人母感天雨生子故稱天子因生以為姓故姓字從女從生生亦聲也）。

Clan name (姓): The Shuowen says: "That by which a person is born. When the mothers of ancient divine men and sages were moved by Heaven to give birth to sons, they were therefore called the Sons of Heaven, and their clan name was determined based on their birth. Hence the character 姓 is formed with 女 'woman' and 生 'birth'; 生 also acts as the phonetic component."