Wa'il bin Dawud has narrated from Ibrahim al-Nakha'i this statement of Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him): "Ablution is required because of what comes out (of the body), not because of what goes in; and the fast (is broken by what) goes in (to the body), not by what comes out."
Al-Tabarani recorded it in al-Mu'jam al-Kabir, and its narrators have been declared trustworthy.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الطهارة / 1253