פירוש על שמות 7:6

ויעש משה ואהרן כאשר צוה ה' אותם, after every instruction from G’d they followed the same procedure. Moses used to announce beforehand what would happen, seeing that he was G’d’s emissary. After that Aaron would translate what Moses had said into diplomatic language.

ויעש משה ואהרון…כן עשו, Moses and Aaron did (as G'd had commanded)..so they did. Why does this verse mention twice that Moses and Aaron did what G'd had commanded them to do? The Torah may be telling us that Moses and Aaron carried out their mission on two levels. 1) The carried out all those instructions of G'd that made sense to them. 2) They tried to understand G'd's purpose in every detail of the instructions they received. By not deviating in a single detail from the instructions they had received, Moses and Aaron proved that their only concern was to carry out G'd's intention to the letter.

כן עשו, “so they did.” The fact is repeated to remind us that Moses and Aaron put their lives in danger every time they threatened Pharaoh with another plague if he did not comply with their request.