Sforno on Leviticus 19:3/ספורנו על ויקרא י״ט:ג׳

1The Torah now begins to explain in detail the commandment to honour father and mother, by writing that everyone is to relate with reverence to his mother and father respectively. These words teach that in addition to providing for aged and economically unstable parents with food, drink and clothing, the children (adults by then) must not look down on their parents who in the meantime have become economically dependent on their children. Our sages spelled this out in Kidushin 31 where they said: “sometimes someone feeds his father the most delicious and expensive dishes while the manner in which he does this contributes to the son’s losing his share in the hereafter, whereas on the other hand, a son could earn his share in the hereafter even by expecting his father to perform physically hard labour.” In the latter case, the son explains to the father lovingly why he cannot offer him luxuries but he treats him with love and concern and listens to his father’s words of advice. Having dealt with the implications of the fifth of the Ten Commandments, the Torah now turns to the fourth of the Ten Commandments, that of Sabbath observance, and writes:

2ואת שבתותי תשמורו, words which do not only refer to the Sabbath of Creation, but to a variety of “Sabbath” legislations such as the “Sabbath” of the land known as sh’mittah, as well as the Sabbath of “money,” i.e. the demand for the lender to forego repayment of past due debts by the debtor at the end of the sh’mittah year. Al these types of “Sabbath” legislation are testimony to the fact that the Creator Who legislates such laws was the originator of the universe, hence His right to demand such obeisances from His creatures.