We (once) sent Noah to his people, and he tarried among them a thousand years less fifty: but the Deluge overwhelmed them while they (persisted in) sin.
The age of a reformer stands for the length of his dispensation
and teaching. Therefore, the period 950 years is not the span of
Noah’s personal physical life (cf. 21:8 or 21:34). In describing the
limit of Noah’s age two words are used here—Sanah and ‘Âmâ. َThe root of the former word gives a sense of badness, while the latter carries sense of goodness. It shows that the first fifty years of
Noah’s dispensation were years of all-around spiritual progress and
regeneration, and that after that period moral degeneration set in.
Sanatin, which has been translated as “year,” is used also for َ
seasons, i.e., one quarter of a year (Tâj; Lisân).
NOORUDDÎN ,ALLÂMAH. (2015). Exegesis of The Holy Qur’ân Commentary and Reflections. http://www.islamicweblibrary.com/wp-content/uploads/2020/10/Exegesis-of-the-Holy-Quran-Commentary-and-Reflections.pdf