Kommentar zu Bamidbar 3:3

הכהנים המשוחים, future priests were not described in such terms as they were not anointed while the High Priest was alive. אשר מלא ידם לכהן, the reason why the sons of Aaron were also anointed with the oil of anointment was to enable them to perform priestly duties, as otherwise there would have been no priests other that Aaron, no one having been born as priest to a father who was a priest. Had they been born after Aaron’s appointment, they would not have required such anointing as heredity would have sufficed.

אלה שמות…המשוחים, These are the names… who had been anointed, etc. When the Torah repeated the word "these" both in verse one and again in our verse it is to stress that only these four sons of Aaron had been anointed. Had the Torah not repeated the word אלה here we could have assumed that other Levites had been anointed seeing that the chapter commenced with the word ואלה, "and these."