It is narrated from Hazrat Abu Qatadah (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: When any one of you drinks something, he should not breathe into the vessel. When entering the toilet, he should not touch his private part with his right hand.
Hadith Referenceمسند احمد / مسند الأنصار رضي الله عنهم / 22634