Asim bin al-Mundhir bin al-Zubayr (may Allah have mercy on him) says: I entered a garden with Ubaydullah bin Abdullah bin Umar, in which there was a pool of water with the skin of a dead camel in it. He performed ablution from it. I said: "Will you perform ablution from it while the skin of a dead camel is in it?" He narrated a hadith to me from his father, that his father narrated from the Prophet (peace and blessings be upon him): "When the water reaches the amount of two or three qullahs (large jars), nothing makes it impure."
The narration of the group who did not express doubt is preferable.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1244