Sforno on Exodus 34:18/ספורנו על שמות ל״ד:י״ח

1את חג המצות תשמור, after the Torah warned us against a graven image meant to improve the quality of our life on this planet, it turns to the commandments the function of which it is (if performed) to assure us of “so-called” success in spring, during the harvest in summer, when gathering the last harvests in autumn, and success in our business endeavours. The Torah enumerates the commandments concerned in the order in which we just listed them. חג המצות למועד חודש האביב, observance of this commandment is to insure that our springtime activities will be blessed. The offering of the firstborns are designed to ensure that our summer time activities will be blessed. This commandment was given immediately after the Exodus. It is intended to ensure that our livestock will be blessed. Third is the commandment to observe the Sabbath, a commandment given to the people at Marah, several weeks before the revelation at Mount Sinai. The objective of Sabbath observance is to ensure that our endeavours during the six days of the week will be blessed with success. The fourth commandment is that of observing the festival of Shavuot, in the early summer, as a result of which the grain harvest will be blessed. The fifth commandment mentioned here is the Sukkot festival, observance of which is to ensure the success of the grape harvest, etc. Deuteronomy 16,17 spells out that the festivals’ aim is to make us conscious of the blessings we have been given by G’d. Having listed specific commandments, the Torah adds a comprehensive commandment applying on each of the three festivals mentioned previously, the pilgrimage to be made by the males to the Temple.This is followed by some details about the festival of matzot in verse 25, followed by a commandment usually observed on Shavuot, the harvest festival, when most of the first fruit has ripened already (verse 26) and the bringing of the first ripened fruit by each farmer accompanied by a thanksgiving prayer is in full swing until Sukkot. This, in turn, is followed by a prohibition not to boil the kid in the milk of its mother, seeing that it is the time of year when most young goats are born. (compare Rosh Hashanah 2) Seeing that at that time the tithe of new born animals is applicable, that is the time when one has to be warned against violating this commandment.