It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Noble Prophet (peace and blessings be upon him) said: "When water is equal to two or three pitchers, impurity does not permeate it."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 4753
Hadith Gradingحکم دارالسلام:حديث صحيح، وهذا إ سناد جيد دون قوله: «أو ثلاث»