On the authority of Anas ibn Malik, that the Messenger of Allah, peace and blessings be upon him, said: "Two ratls of water suffice for the ablution."(1)

This is a strange hadith; we do not know it except from the narration of Sharik with this wording.

Shu'bah narrated from 'Abdullah ibn 'Abdullah ibn Jabr, from Anas ibn Malik, that the Prophet, peace and blessings be upon him, used to perform ablution with a makkuk and perform the major ablution (ghusl) with five makakik.(2)

Sufyan al-Thawri narrated from 'Abdullah ibn 'Isa, from 'Abdullah ibn Jabr, from Anas, that the Prophet, peace and blessings be upon him, used to perform ablution with a mudd and perform the major ablution with a sa'. This is more authentic than the narration of Sharik.(3)

--------------------------------------------
(1) Its chain is weak—Sharik, namely Ibn 'Abdullah, was poor in memorization. Abu Dawud (95) narrated it with the wording: "The Prophet, peace and blessings be upon him, used to perform ablution with a vessel that held two ratls, and perform the major ablution with a sa'." It appears with this wording in the Musnad (12843), and with the wording of the compiler (12839), and in Sharh al-Sunnah of al-Baghawi (278). See what follows.

(2) Authentic. Muslim (325) and al-Nasa'i 1/57, 127, and 179 narrated it. It is in the Musnad (12105) and Sahih Ibn Hibban (1203) and (1204). The makkuk is a measuring vessel. Abu Khaythamah said: it is the mudd. Al-Nawawi said: perhaps what is meant by makkuk here is the mudd, as stated in the other narration: he performed ablution with a mudd and the major ablution with a sa', up to five mudds.

(3) From his saying: "Sufyan narrated..." to this point, we have established it from (L) by the narration of Abu 'Ali al-Sibkhi, and from the margin of (A), and it does not appear in the rest of our manuscript sources. The narration of Sufyan al-Thawri was transmitted by Ahmad in the Musnad (13788) and Abu 'Awanah 1/233.