וַֽיְחִי־שֵׁ֕ת חָמֵ֥שׁ שָׁנִ֖ים וּמְאַ֣ת שָׁנָ֑ה וַיּ֖וֹלֶד אֶת־אֱנֽוֹשׁ׃
Seth, ayant vécu cent cinq ans, engendra Énos.
Chizkuni
ויולד בן, “he begat a son;” the Torah did not write: “he sired Noach,” as it did in similar situations, i.e. Genesis 5,6; 5,9; Judges 11,1; Chronicles I 1,34, et al. The reason is that Noach warranted an extra verse seeing that the whole human race today exists thanks to him. The entire human race was destroyed during his lifetime; only he, his wife and his children and their wives, having been saved. A different interpretation: Metushelach, Lemech’s father, advised his son not to immediately name him as his contemporaries who were worshipping all kinds of idols, and who would curse and kill people who were monotheists, would try and kill him by telling their idols his name. After Noach had married and had sired a son, his father turned to his father again and was told then to call him Noach, as he had the potential to save all of mankind if they would follow his lifestyle. If not, they would all perish before they could harm him. (Compare Torah sh’leymah item 71 on this verse)