يَـٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوٓا۟ إِن جَآءَكُمْ فَاسِقٌۢ بِنَبَإٍ فَتَبَيَّنُوٓا۟ أَن تُصِيبُوا۟ قَوْمًۢا بِجَهَـٰلَةٍ فَتُصْبِحُوا۟ عَلَىٰ مَا فَعَلْتُمْ نَـٰدِمِينَ
Yaaa ayyuhal lazeena aamanoo in jaaa'akum faasqum binaba in fatabaiyanooo an tuseeboo qawmam bijahalatin fatusbihoo 'alaa maa fa'altum naadimeen
Believers, if a troublemaker brings you news, check it first, in case you wrong others unwittingly and later regret what you have done,
You who believe, if a wrongdoer brings you news, verify it — lest you harm a people in ignorance and come to regret what you have done.
The duty here falls on whoever receives the report, since they are the ones positioned to act on it and cause harm. Traditional accounts tie the verse to news brought back about the Banu al-Mustaliq that proved false, with an expedition against them nearly launched on the strength of it. Later scholars built much of the assessment of hadith transmitters on this instruction, treating the character of a source as part of the evidence.