Al-Hasan (al-Basri) narrates from five noble Companions (may Allah be pleased with them): Sayyiduna Ali bin Abi Talib, Sayyiduna Ibn Mas'ud, Sayyiduna Hudhayfah, Sayyiduna Imran bin Husayn and one other Companion (may Allah be pleased with them). One of them said: "I do not care whether I touched my private part or the tip of my nose." Another said: "My ear." Another said: "My thigh." And yet another said: "My knee."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 9186