Yahya bin Yahya (may Allah have mercy on him) was rebuking al-Husayn bin Mansur for entering into the 'adalah (the office of vouching for witnesses). Then he said: Did you not yourself relate from Sufyan bin Uyaynah (may Allah have mercy on him) that he said: Do not be one who vouches for witnesses, nor one whom such a voucher knows? Then Yahya bin Yahya (may Allah have mercy on him) said: The 'adalah is nothing but a little platter that is sent to one of them.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب آداب القاضي / 20241