(a) Sufyan and Ibn Jurayj (may Allah have mercy on them both) met and debated touching the private part. Ibn Jurayj (may Allah have mercy on him) said: Ablution is to be performed because of it; and Sufyan (may Allah have mercy on him) said: Ablution is not to be performed. Sufyan (may Allah have mercy on him) said: Tell me, if a man holds semen in his hand, what is required of him?
Ibn Jurayj (may Allah have mercy on him) said: He should wash his hand. He asked: Which is greater, semen or touching the private part? Ibn Jurayj (may Allah have mercy on him) said: It is Satan who has put this into your heart.
(b) The Shaykh said: What Ibn Jurayj (may Allah have mercy on him) meant is that the Sunnah is not to be set against analogy.
(c) Imam al-Shafi'i (may Allah have mercy on him) mentioned in the narration of al-Za'farani that whoever among the Companions (may Allah be pleased with them) said there is no ablution in it said so from his own opinion, and whoever made ablution obligatory in it did so only by following (the Sunnah).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 650