بـسـم الله والحـمـد لله والـصلاة والـسـلام عــلى رسـول الله، وبـعـد
In recent times it has become apparent that many of those who follow the Sunnah of eating using the fingers of the right hand abandon the Sunnah of drinking with the right hand. When questioned about this practice they excuse themselves by stating that if they do so, their cup will get dirty. They are willing to dirty (abandon) the Sunnah, but they are not willing to dirty the cup! Subhaan-Allaah!
The following are a few Ahaadeeth which prohibit the consumption of food AND drink with the left hand.
Narrated Jaabir ibn `Abdullaah رضي الله عنه: Allaah's Messenger صلى الله عليه وسلم said: “Do not eat with your left hand, for the Satan eats with his left hand.” [Saheeh Muslim (3770)]
Narrated `Abdullaah ibn `Umar رضي الله عنهما: Allaah's Messenger صلى الله عليه وسلم said: “When any one of you intends to eat (a meal), he should eat with his right hand, and when he (intends) to drink he should drink with his right hand, for the Satan eats with his left hand and drinks with his left hand.” [Saheeh Muslim (3771)]
Narrated Salamah ibn al-Akwa` رضي الله عنه: A person ate in the presence of Allaah's Messenger صلى الله عليه وسلم with his left hand, whereupon he صلى الله عليه وسلم said: “Eat with your right hand.” He said: I cannot do that, whereupon he (the Prophet صلى الله عليه وسلم) said: “May you not be able to do that.” It was Takabbur (vanity) that prevented him from doing it, and thereafter he could not raise it (the right hand) up to his mouth. [Saheeh Muslim (3773)]
Verily eating and drinking with the left hand is not a small matter. If it were not that important, the Prophet صلى الله عليه وسلم would not have supplicated against that person.