Sayyiduna Talq bin Ali (may Allah be pleased with him) said: We came to the Prophet (peace and blessings be upon him) as a delegation; we gave him (peace and blessings be upon him) our pledge of allegiance and prayed with him (peace and blessings be upon him). A Bedouin man came and said: O Messenger of Allah (peace and blessings be upon him), what do you think about a man who touches his private part after performing ablution? He (peace and blessings be upon him) said: "It is only a part or a piece of his body." (b) The Shaykh said: Muhammad bin Jabir al-Yamami and Ayyub bin Utbah narrate it from Qays bin Talq, and both are da'if (weak).
Abu Bakr Ahmad bin Ishaq al-Sibghi said: Mulazim is open to question. Ikrimah bin Ammar narrated it from Qays as mursal; he is the best of those who narrated it from Qays, yet his reliability is disputed: Yahya bin Sa'id al-Qattan and Ahmad bin Hanbal criticized him, and al-Bukhari declared him very weak. As for Qays bin Talq, al-Shafi'i said: We asked about Qays and found no one who knew him in a way that would allow us to accept his report. Yahya bin Ma'in said: The hadith of Qays bin Talq is not used as proof. Abu Hatim and Abu Zur'ah said: Qays bin Talq is not one by whom proof is established; they deemed it weak and did not accept it as established.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 645