Thou shalt not offer the blood of my sacrifice with leaven; neither shall the sacrifice of the feast of the passover be left unto the morning.
The Israelites had just made a calf and called it a feast; now God prescribes His own feasts to guard them from that snare. Serious godliness is a continual feast, and joy in God always. Even in harvest's press, the Sabbath must not yield; the work will prosper better for honoring it than for abandoning it.
AI summary
Commenting on Exodus 34:18-27
And he was there with the Lord forty days and forty nights,.... These were other forty days and nights, besides those he had been with the Lord, when he came down and broke the two tables in his hand, on sight of the idolatry of the people; yea, not only the Jewish writers think that he was on the mount three times forty days and...
The blood of my sacrifice - That is, the paschal lamb. See Clarke on Exo 23:18 (note).