וַיְהִ֡י כִּ֣י הִקִּיפֽוּ֩ יְמֵ֨י הַמִּשְׁתֶּ֜ה וַיִּשְׁלַ֧ח אִיּ֣וֹב וַֽיְקַדְּשֵׁ֗ם וְהִשְׁכִּ֣ים בַּבֹּקֶר֮ וְהֶעֱלָ֣ה עֹלוֹת֮ מִסְפַּ֣ר כֻּלָּם֒ כִּ֚י אָמַ֣ר אִיּ֔וֹב אוּלַי֙ חָטְא֣וּ בָנַ֔י וּבֵרֲכ֥וּ אֱלֹהִ֖ים בִּלְבָבָ֑ם כָּ֛כָה יַעֲשֶׂ֥ה אִיּ֖וֹב כָּל־הַיָּמִֽים׃ (פ)
И было так, когда прошли дни их пиршества, что Иов послал и освятил их, и встал рано утром, и принес жертвы всесожжения в соответствии с числом их всех; Иов сказал:'Возможно, мои сыновья согрешили и поносили Бога в своих сердцах.' Так делал Иов постоянно.
Rashi
Now it would come about when the cycle of the feasting days would be over When the days of the feasting would be over, Job would act in this manner; upon every termination of the seven days on which the days of feasting rotated, he would send and summon them (ויקדשם) ; i.e., he would prepare them and summon them, as in (Num. 11:18). “Prepare yourselves for tommorow.”
Malbim
Having eliminated or dismissed all the normal explanations that might possibly be offered for Job's afflictions, the Prologue now goes on to relate the real reason why these great afflictions befell him.
Rashi
and offer up... early in the morning The meaning is that he would offer up burnt-offerings early. Therefore, Scripture wrote in the future tense, that he was wont to do so always at the end of every seven days.
Rashi
and blasphemed Heb. וברכו, lit. will do. A euphemism [used in] referring to the Most High.
Rashi
So would Job do Heb. יעשה, lit. will do. He would always do in this manner. When Scripture writes about a constant occurrence, sometimes it writes in the past tense, and sometimes in the future tense.