Marwan bin Al-Hakam and Al-Miswar bin Makhrama told him that when the Muslims were permitted to set free the captives of Hawazin, Messenger of Allah ﷺ said, "I do not know who amongst you has agreed (to it) and who has not. Go back so that your 'Urafa' may submit your decision to us." So the people returned and their 'Urafa' talked to them and then came back to Messenger of Allah ﷺ and told him that the people had given their consent happily and permitted (their captives to be freed). (Using translation from Bukhārī 7176)   

أَنَّ رَسُولَ اللهِ ﷺ حِينَ أَذِنَ لِلنَّاسِ فِي عِتْقَ سَبْيِ هَوْازِنَ قَالَ إِنِّي لَا أَدْرِي مَنْ أَذِنَ مِنْكُمْ مِمَنْ لَمْ يَأْذَنْ فَارْجِعُوا حَتَّى يَرْفَعَ إِلَيْنَا عُرَفَاؤُكُمْ أَمْرَكُمْ فَرَجَعَ النَّاسُ فَكَلَّمَهُمْ عُرَفَاؤُهُمْ فَرَجَعُوا إِلَى رَسُولِ اللهِ ﷺ فَأَخْبَرُوهُ أَنَّ النَّاسَ قَدْ طَيَّبُوا وَأَذِنُوا  

[Machine] When Umar assumed the caliphate, he established the obligatory duties, recorded the registers, acquainted the knowledgeable individuals, and introduced me to my companions.  

لَمَّا وَلِيَ عُمَرُ ؓ الْخِلَافَةَ فَرَضَ الْفَرَائِضَ وَدَوَّنَ الدَّوَاوِينَ وَعَرَّفَ الْعُرَفَاءَ وَعَرَّفَنِي عَلَى أَصْحَابِي