וַיֹּ֣אמֶר אַהֲרֹ֔ן אַל־יִ֥חַר אַ֖ף אֲדֹנִ֑י אַתָּה֙ יָדַ֣עְתָּ אֶת־הָעָ֔ם כִּ֥י בְרָ֖ע הֽוּא׃
Harun menjawab: “Janganlah amarah tuanku bangkit. Engkau sendiri mengenal bangsa ini, bahwa mereka cenderung kepada kejahatan.
Rashi
כי ברע הוא [THOU KNOWEST THE PEOPLE] THAT THEY ARE SET ON EVIL — They always go on the wrong way and with temptations, before the Omnipresent.
Chizkuni
כי ברע הוא, “that they are bent on evil;” they have evil intentions; if I had not had made the calf for them they would have crowned a king for themselves and the final result would have been bitter for them. (Baaley Tossaphot)
Da'at Zekenim
כי ברע הוא, “when it is bent on evil.” If he had not done what he did in response to their demand, they would have appointed a new leader with even worse consequences.