Surah Al-Isra 17:47

نَّحْنُ أَعْلَمُ بِمَا يَسْتَمِعُونَ بِهِۦٓ إِذْ يَسْتَمِعُونَ إِلَيْكَ وَإِذْ هُمْ نَجْوَىٰٓ إِذْ يَقُولُ ٱلظَّـٰلِمُونَ إِن تَتَّبِعُونَ إِلَّا رَجُلًا مَّسْحُورًا

We are most knowing of how they listen to it when they listen to you and [of] when they are in private conversation, when the wrongdoers say, "You follow not but a man affected by magic."

Translation: Saheeh International

Tafsir

We know best what they listen to the reason for which they listen to it in order to mock it when they listen to you to your recital and when they are in secret counsel holding secret talks among themselves in other words when they talk when idh substitutes for the preceding idh ‘when’ the evildoers say in their secret …

Excerpt from Tafsir al-Jalalayn, commentary on 17:47, via Quran.com. The reader has the full commentary and 9 more tafsirs.