"إذا شرب أحدكم فلا يتنفس في الإناء وإذا أتى الخلاء فلا ¤ يمس ذكره بيمينه ولا يتمسح بيمينه"
The Prophet (peace and blessings be upon him) said:
"When one of you drinks something, let him not breathe into the vessel; and when he goes to relieve himself, let him not touch his private part with his right hand, nor clean himself (istinja) with his right hand."
Hadith Referenceصحیح الجامع الصغیر / حرف الألف / 625