And among them are men who listen to thee, but in the end, when they go out from thee, they say to those who have received Knowledge, “What is it he said just then?” Such are men whose hearts Allah has sealed, and who follow their own lusts.
The case here referred to is that of the Hypocrites who
came to the assemblies of Islam in Madinah and
pretended to listen to the Prophet’s teaching and
preaching. But their heart and mind were not in learning
righteousness, but in carping at things they saw and
heard. When they got out, they knew nothing of the teaching,
but on the contrary asked foolish and ignorant questions,
such as might raise doubts.
Yusuf Ali, Abdullah. Translation and Commentary of the Quran. (surah 47 verse 16). Quran Arabic with English Translation & Commentary (Tafsir) by Abdullah Yusuf Ali, Free Download (quran4u.com)