Abu Dawud
Purification (Kitab Al-Taharah)
Book Number: 001 / Hadith Number: 53
Narated By 'Ammar b. Yasir : The Apostle of Allah (pbuh) said: The rinsing of the mouth and snuffing up water in the nose are acts that bear the characteristics of fitrah(nature). He then narrated a similar tradition (as reported by 'Aisha), but he did not mention the words "letting the beard grow." He added the words "circumcision" and "sprinkling water on the private part of the body." He did not mention the words "cleansing oneself after easing."
Abu Dawud said: A similar tradition has been reported on the authority of Ibn 'Abbas. He mentioned only five sunnahs all relating to the head, one of them being parting of the hair; it did not include the wearing of the beard.
Abu Dawud said: The tradition as reported by Hammad has also been transmitted by Talq b. Habib, Mujahid, and Bakr b. 'Abd Allah b. al-Muzani as their own statement (not as a tradition of the Prophet). They did not mention the words "leting the beard grow). The version transmitted by Muhammad b. 'Abd Allah b. Abi Maryam, Abu Salamah, and Abu Hurairah from the Prophet (pbuh) mentions the words "letting the beard grow." A similar tradition has been reported by Ibrahim al-Nakha'i. He mentioned the words "wearing the beard and circumcision."