Rashi on Exodus 23:12/רש"י על שמות כ״ג:י״ב

1וביום השביעי תשבת [SIX DAYS SHALT THOU DO THY WORK] AND ON THE SEVENTH DAY THOU SHALT LEAVE OFF — Even in the Sabbatical year you shall not abrogate the weekly Sabbath: you shall not say, “Since the whole year bears the name of ‘Sabbath’, the weekly Sabbath need not to be observed” (Mekhilta).

2למען ינוח שורך means, give it (the animal) some satisfaction (ניח) by permitting it to pull up and eat grass from the ground as it pleases. Or, perhaps, this is not the meaning but it means that is must rest: that one must tie it up in its stall so that it does no work in the field! You will, however, admit this is no satisfaction but a source of annoyance (Mekhilta).

3בן אמתך THE SON OF THY HANDMAID — Scripture speaks of an uncircumcised Canaanitish servant; (that the circumcised servant should rest is already mentioned in Deuteronomy 5:14: עבדך ואמתך כמוך) (cf. Mekhilta).

4והגר means a גר תושב, a proselyte settler (one who renounces idolatry and thus acquires limited citizenship in Palestine).