This narration is also similar.
(b) Imam al-Shafi'i (may Allah have mercy on him) said that this indicates there is no fixed measure for it, other than that the bath be complete, and Allah knows best. (c) It is narrated from the Prophet (peace and blessings be upon him) concerning a person in a state of major ritual impurity: "When you find water, let it touch your skin." No measure is fixed in it either. (d) The Shaykh said that this hadith has already passed, and, if Allah wills, it will be mentioned again later.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 931