Sforno on Exodus 34:26/ספורנו על שמות ל״ד:כ״ו

1ראשית בכורי אדמתך תביא, by doing this you will assure yourself of success in growing fruit as spelled out in Ezekiel 44,30 וראשית כל בכורי כל...תתנו לכהן להניח ברכה אל ביתך, “the first of all your early ripening crops… you shall give to the priest so that blessing will come to rest on your house.”

2לא תבשל גדי, as this is something the gentiles do, believing that it assures them success in raising fruit and cattle.