Rashi on Exodus 32:29/רש"י על שמות ל״ב:כ״ט

1מלאו ידכם CONSECRATE YOURSELVES — You who are killing them (your own relatives) will by this very act install yourselves as priests of the Omnipresent God,

2כי איש FOR EVERY MAN among you will consecrate himself בבנו ובאחיו BY HIS SON AND HIS BROTHER (by their death at his hand).