יֹ֣אבַד י֭וֹם אִוָּ֣לֶד בּ֑וֹ וְהַלַּ֥יְלָה אָ֝מַ֗ר הֹ֣רָה גָֽבֶר׃
Périsse le jour où je suis né, la nuit qui a dit: "Un homme a été conçu!"
Rashi on Job
in which I was to be born This is a future expression, that he was saying, “Would that the day in which I was destined to be born be lost, and then I would not have been born.”
Malbim on Job
Convinced that the shattering series of catastrophes that had befallen him was totally unwarranted and that, as such, it could not have originated with God, for that would imply an imperfection in His Governance, Job attributes its occurrence to the bad luck of his birth, namely, to his horoscope. In which case, it would have been better had he never been conceived or born.
Rashi on Job
and the night That too should have been lost.