Question is in the title.
I thought they didn’t leaven their bread because they were in a hurry to get out of Egypt… assuming it ever happened.
I think the answer is already there in the question. They were preparing to leave.
According to Exodus 12:39 it’s indeed a result of the rush with which they had to leave, but just a few verses before, in Exodus 12:19-20, there’s an explicit prohibition against leavened bread for the seven days before they left. I suppose that’s retconned.
To give them time to practice and perfect the matzoh process, I bet.
Don’t leaven, just leave!
Seven days? Yikes! Just how long did they let bread rise in those days? Or was it a case of “we could leave at any momnet”?
This, mostly, I suspect.
Also, in the days before buying a little packet of yeast from the grocery store, you had to cultivate your own, similar to what now gets called “friendship bread”. The rising of the dough itself wouldn’t take seven days, but the culturing of the yeast might.
Uh, matzo doesn’t use yeast, that’s sort of the point.
The “real” reason is likely that the pagans who would eventually become Jews had some spring harvest festival where only unleavened bread was eaten, and the Exodus story later got grafted onto that much like Jesus’ birthday got grafted onto Saturnalia.
No, that doesn’t explain anything at all, because then you’re just pushing the question back to why the pre-Jews ate unleavened bread.
Well, that’s true, but it does resolve the question of why Jews did/do so. I doubt there’s any way to tell what reason the ancient Caananites had for the prohibition.
Yeah, Exodus 12 is literarily very interesting, as it segues from a narration of events into instructions for how to observe a holiday commemorating those events.
The basic Jewish Sunday school teacher answer is that they didn’t have time for the bread to rise, but the Biblical text itself is contradictory on the topic.