The table below presents an aligned extract of verses or verselets in Ex40-29a, Ex40-31. Both verses/verselets discuss the procedures when the Temple was erected / conscecrated. The alignment justifies the Rashi comment that: Note the contrast in subjects: he (Moses) offered vs Moses, Aaron, and his sons washed. It was Moses not Aaron who offered the daily offering during the conscecration of the Temple. Indeed, just as Moses offered sacrifices during the 7 days of consecration (Lv08-15,Lv08-19,21, etc) so too he offered on the 8th day since Aaron and his sons had not yet completed all the induction sacrifices (Lv08-01:04) and was not yet a priest. Since there were no priests, Moses did the offering.

Verse	Text of Verse	Rashi comment
Ex40-29	And he[Moses] put the altar of burnt offering by the door of the tabernacle of the Tent of the Meeting, and he offered upon it the burnt offering and the meal offering; as the Lord commanded Moses.	Note the contrast in subjects: he (Moses) offered vs Moses, Aaron, and his sons washed. It was Moses not Aaron who offered the daily offering during the conscecration of the Temple. Indeed, just as Moses offered sacrifices during the 7 days of consecration (Lv08-15,Lv08-19,21, etc) so too he offered on the 8th day since Aaron and his sons had not yet completed all the induction sacrifices (Lv08-01:04) and was not yet a priest. Since there were no priests, Moses did the offering.
Ex40-31	And Moses and Aaron and his sons washed their hands and their feet there;

Advanced Rashi: We can strengthen the Rashi derivation. All of Ex40 uses Moses-he to indicate the subject of the sentence until Ex40-31 when the subject switches to Mosees, Aaron and his sons. This contrast indicates a switch in subject from he = Moses to Moses, Aaron and his children. The alignment table above simply contrasts two of the many verses in the chapter.