Ahmad bin al-Abbas said: I said to Yahya bin Ma'in: Do you know (this) from al-Zuhri, from Abu Salamah, from Abu Hurayrah (may Allah be pleased with him), from the Prophet (peace and blessings be upon him), that he said: "The prayer is to be repeated for blood the size of a dirham"? He said: No, by Allah. Then he said: From whom (did you get it)? I said: Muhriz bin Awn narrated it to us. He said: Trustworthy; from whom? I said: From al-Qasim bin Malik al-Muzani. He said: Trustworthy; from whom? I said: From Rawh bin Ghutayf. (I said:) What do you say, O Abu Zakariyya? I think the problem has come to us only from Rawh bin Ghutayf. He said: Yes.
Abu Ahmad (Ibn Adi) said: As far as I know, no one other than Rawh bin Ghutayf narrates this from al-Zuhri, and it is munkar (denounced) with this chain. And according to what has reached me from Muhammad bin Yahya al-Dhuhli, he said: I fear that this is fabricated, and this Rawh is majhul (unknown).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4095