Or HaChaim on Exodus 35:20/אור החיים על שמות ל״ה:כ׳

1 ויצאו כל עדת בני ישראל מלפני משה. The whole congregation of Israelites departed from the presence of Moses. The Torah emphasises that they all left simultaneously, eager to bring their contributions for this sacred project.

2מלפני משה. From the presence of Moses. This is mentioned to indicate that contrary to general practice, the Israelites did not wait for Moses to formally give them permission to leave this assembly. This was in contrast to a halachic ruling recorded in Yuma 53 according to which a disciple must not leave the presence of his teacher without first obtaining permission to do so. The Israelites reasoned that seeing Moses had said: "take from yourselves a gift, etc." the fact that he stopped addressing them was equivalent to his having dismissed them. Alternatively, the Israelites' love to contribute to the sacred project made them forget their good manners. They may have been anxious to contribute what they could before Moses himself would anticipate them. Moses personally was very wealthy and certainly sufficiently motivated to contribute so much of his own that little would be left for the average Israelite to contribute.