Exodus 5:4

And the king of Mizraim said to Mosheh and Aharon, Why do you make the people cease from their labours? Go to your work.

WHEREFORE DO YE, MOSES AND AARON…? Pharaoh asked them for their names, and he mentioned them by name in a manner indicating respect.

TAPHRI’U’ THE PEOPLE FROM THEIR WORK. Onkelos translated: t’vatlu (you cause them to idle from their work). Similarly: ‘porei’a’ (refuseth) instruction; as meaning: “taking them away.” Ramban therefore calls attention to Onkelos, who interpreted it as meaning “idle,” “making to nought all their work.” ‘vatiphr’u’ (and ye have set at nought) all my counsel., 1:25.

GET YOU TO YOUR BURDENS. If we follow the simple interpretation of Scripture, reference here is to the work for the king, since Moses and Aaron were part of the [Hebrew] people for at this time they came before him with all the people. But he did not listen to them and commanded them: “Return you all to the work.” Later when Moses and Aaron returned before Pharaoh and he said to them, Show a wonder for you, and they did so, they appeared to him like the magicians, sorcerers, and wise men, and he showed them respect. Still later, when the plagues began coming upon him, he was in dread fear of them.
It appears furthermore that not all the children of Israel worked all the time for Pharaoh in mortar and in brick, for in that case they would have filled the whole land of Egypt with cities. Rather, they worked in levies, and he pressed his yoke upon them by taking many of the Israelites [into his labors].

תפריעו, you make them idle, or “detach them” from their regular duties. The word פרע in Numbers 5,18 means to detach the hair of the woman from her head.

לסבלותיכם, to your regular occupation, and neither interrupt your agenda nor try to disrupt my own agenda.

לכו לסבלתיכם, “get to your labours!” Rashi comments that Moses and Aaron did not personally have to perform manual labour, as they belonged to the tribe of Levi which was exempt from that. Accordingly, what Pharaoh meant was that they should attend to their affairs and not meddle in those of the other tribes. (Sh’mot Rabbah 5,15.) According to the Midrash there, the members of that tribe already at the very outset, when Pharaoh “invited” the people to build fortifications and show their patriotism, explained that they could not engage in such manual labour as they were destined to perform different holy tasks in the Temple in the future. They would not engage in such activities regardless of how well Pharaoh would pay them for this. They remained exempt from such labour. When Moses grew up and saw that the other tribes were forced to work seven days a week, he went to Pharaoh and explained to him that unless he gave these people at least one day of rest during each week, instead of their producing more bricks, they would fall over dead from exhaustion and produce no bricks at all. This made sense to Pharaoh, and he empowered Moses to tell the people that they could select one day of the week as their day of rest. A miracle occurred and they chose the Sabbath as their day of rest. This is why Moses was able to tell the people (Exodus 16,29) that G–d had given them a day of rest on the Sabbath. They themselves had already chosen this day as their day of rest while still slaves in Egypt.