Sufyan bin Abd al-Malik related that Abdullah bin al-Mubarak (may Allah have mercy on him) said: "I saw Rawh bin Ghutayf, the narrator of the hadith attributed to the Prophet (peace and blessings be upon him) about blood the size of a dirham. I sat with him in a gathering, and I began to feel ashamed before my companions lest they see me sitting with him, because of the abundance of munkar (denounced) narrations among the hadiths he narrated."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4094