"And the people took up their dough before it was leavened" (Exodus 12:34) — teaching that it was about to leaven [but did not]. "Their kneading-troughs bound up in their garments upon their shoulders" — what they had left over of the unleavened bread and what they had left over of the bitter herbs. Another interpretation: "Their kneading-troughs bound up in their garments upon their shoulders" — they had nothing of provisions [to carry]. And why would one take this [small amount]? But in the end of the matter Scripture praises them, that they were wealthy people. Rather, it teaches that they took in their hands only a small amount, and a blessing entered into it, and they ate from it thirty-one days, and it was as fine for them as the manna.
Israel Carried Their Dough Before It Leavened With a Blessing Inside
Mekhilta DeRabbi Shimon Ben Yochai 12:34
וישא העם את בצקו טרם יחמץ מלמד שקרב להחמיץ: משארותם צרורות בשמלותם על שכמם. מה ששיירו מן המצה ומה ששיירו מן המרור: ד"א משארותם צרורות בשמלותם על שכמם לא היה בידם מהליכות ומה לזו ליטול והלא לסוף הענין הכתוב משבחן שהיו בני אדם עשירים אלא מלמד שלא נטלו בידם אלא דבר מועט ונכנסה בו ברכה ואכלו ממנו אחד ושלשים יום שהיה יפה להן כמן: