And Aaron had already told them before [the return of Moses], "O (20:90)

﴿وَلَقَدْ قَالَ لَهُمْ هَارُونُ مِن قَبْلُ يَا قَوْمِ إِنَّمَا فُتِنتُم بِهِ ۖ وَإِنَّ رَبَّكُمُ الرَّحْمَٰنُ فَاتَّبِعُونِي وَأَطِيعُوا أَمْرِي﴾
[ طه: 90]

20:90 And Aaron had already told them before [the return of Moses], "O my people, you are only being tested by it, and indeed, your Lord is the Most Merciful, so follow me and obey my order."

Aaron had said to them before Moses returned to them: “The making of the calf from gold and its mooing are only to test you, to distinguish the believer from the disbeliever.
And your Lord, O people, is Allah, so follow me by worshipping Him alone and obey my command to leave worshipping others besides Him”.

And Harun (Aaron) indeed had said to them beforehand: "O my people! You are being tried in this, and verily, your Lord is (Allah) the Most Beneficent, so follow me and obey my order."

phonetic Transliteration

Walaqad qala lahum haroonu min qablu ya qawmi innama futintum bihi wainna rabbakumu alrrahmanu faittabiAAoonee waateeAAoo amree

Abdullah Yusuf Ali - Translation

Aaron had already, before this said to them: "O my people! ye are being tested in this: for verily your Lord is (Allah) Most Gracious; so follow me and obey my command."

Safi-ur-Rahman al-Mubarakpuri

And Harun indeed had said to them beforehand: "O my people! You are being tried in this, and verily, your Lord is (Allah) the Most Gracious, so follow me and obey my order."

Page 318 English transliteration