It was narrated from 'Ubaidullah bin 'Abdullah bin 'Umar that his father said:"The Messenger of Allah said: 'If the water is the amount of two or three Qullah, nothing can make it impure (Najis).'" (Sahih) Another chain with similar wording
Hadith No. 518
Sunan Ibn Majah
Gradings:
Al-Albani:
Sahih
Muhammad Fouad Abd al-Baqi:
Sahih
Zubair Ali Zai:
Sahih