Ta-Ha
وَلَقَدْ قَالَ لَهُمْ هَـٰرُونُ مِن قَبْلُ يَـٰقَوْمِ إِنَّمَا فُتِنتُم بِهِۦ ۖ وَإِنَّ رَبَّكُمُ ٱلرَّحْمَـٰنُ فَٱتَّبِعُونِى وَأَطِيعُوٓا۟ أَمْرِى
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."
Nearby ayahs help place verse 20:90 in sequence and meaning.
فَأَخْرَجَ لَهُمْ عِجْلًا جَسَدًا لَّهُۥ خُوَارٌ فَقَالُوا۟ هَـٰذَآ إِلَـٰهُكُمْ وَإِلَـٰهُ مُوسَىٰ فَنَسِىَ
And he extracted for them [the statue of] a calf which had a lowing sound, and they said, "This is your god and the god of Moses, but he forgot."
أَفَلَا يَرَوْنَ أَلَّا يَرْجِعُ إِلَيْهِمْ قَوْلًا وَلَا يَمْلِكُ لَهُمْ ضَرًّا وَلَا نَفْعًا
Did they not see that it could not return to them any speech and that it did not possess for them any harm or benefit?
قَالُوا۟ لَن نَّبْرَحَ عَلَيْهِ عَـٰكِفِينَ حَتَّىٰ يَرْجِعَ إِلَيْنَا مُوسَىٰ
They said, "We will never cease being devoted to the calf until Moses returns to us."
قَالَ يَـٰهَـٰرُونُ مَا مَنَعَكَ إِذْ رَأَيْتَهُمْ ضَلُّوٓا۟
[Moses] said, "O Aaron, what prevented you, when you saw them going astray,