לֹא־יִקְשֶׁ֣ה בְעֵינֶ֗ךָ בְּשַׁלֵּֽחֲךָ֙ אֹת֤וֹ חָפְשִׁי֙ מֵֽעִמָּ֔ךְ כִּ֗י מִשְׁנֶה֙ שְׂכַ֣ר שָׂכִ֔יר עֲבָֽדְךָ֖ שֵׁ֣שׁ שָׁנִ֑ים וּבֵֽרַכְךָ֙ יְהוָ֣ה אֱלֹהֶ֔יךָ בְּכֹ֖ל אֲשֶׁ֥ר תַּעֲשֶֽׂה׃ (פ)
Тебе не покажется тяжело, когда ты отпустишь его на свободу; ибо вдвойне от найма наемника он прослужил тебе шесть лет; и Господь, Бог твой, благословит тебя во всем, что ты делаешь.
Rashi
כי משנה שכר שכיר [IT SHALL NOT SEEM HARD UNTO THEE WHEN THOU LETTEST HIM GO FREE …] FOR [HE HATH BEEN WORTH] A DOUBLE HIRED SERVANT [UNTO THEE] — From here they (the Rabbis) derived the law that a Hebrew servant has to do service both by day and by night, and that is double as much as the labor of a man hired for day work only. And what is his service during the night? That his master gives him a Canaanite maid-servant with the object of raising children, and the children belong to the master (Sifrei Devarim 123:1; Kiddushin 15a).
Ibn Ezra
you must not begrudge… We find the verse “three years, as the years of a hireling” [Isaiah 16: 14] from which we learn that a man is not permitted to hire himself out for more than three years. This principle applies in equal force to the employer (that is, he who pays his wage).
Rashbam
לא יקשה בעיניך, when you dismiss her from your service having given him money, etc. משנה, double שכר שכיר, the wages paid to a hired hand, (the Torah knows that you paid him 6 years’ wages in advance, and with what you are giving when he leaves he has in effect received twice what a hired hand would have received.) In recognition of how you have treated him, G’d will bless you in all your undertakings. The meaning of this paragraph is similar to the admonition of the Torah in verse 10 and the use of the term רע בעיניך occurs also in such a sense in Deut. 28,56 when the reaction of even a mother and wife to the pressures of famine are described. רועת עין, describes envy and jealousy in matters financial. The same is true of the expression קשיות הלב, being hard-hearted. Both expressions refer to the feelings of a person when he has to give of his money to others who he does not feel have a claim on his money, on his generosity. Those commentators who understand our verse as speaking of the employer feeling put out at having to release their worker and the Torah telling the employer that he had no cause for the worker had worked diligently for six years are in error. The master knew in advance that after six years the contract was complete and the worker would be free to go. What possible reason could the employer have of being jealous of that arrangement?
Furthermore, the Torah should not have written משנה שכר שכיר, but merely משנה שכיר. Some commentators take the view that the words משנה שכיר refer to the six years, seeing that the average period for which a labourer was hired used to be 3 years, so that the word משנה would refer to the fact that this labourer worked for twice that period. The idea that the standard period was three years is reflected in Isaiah 16,14 This is also senseless, seeing that in Isaiah 21,16 we are told that the average period of hire was precisely a year, no longer. It follows that the words כשני שכיר (as the years of a hired hand) mean precisely 3 years just as when he is hired for a year it means precisely a year.
Furthermore, the Torah should not have written משנה שכר שכיר, but merely משנה שכיר. Some commentators take the view that the words משנה שכיר refer to the six years, seeing that the average period for which a labourer was hired used to be 3 years, so that the word משנה would refer to the fact that this labourer worked for twice that period. The idea that the standard period was three years is reflected in Isaiah 16,14 This is also senseless, seeing that in Isaiah 21,16 we are told that the average period of hire was precisely a year, no longer. It follows that the words כשני שכיר (as the years of a hired hand) mean precisely 3 years just as when he is hired for a year it means precisely a year.