Drinking what is leftover by another person

Q182 :Some scholars are of the opinion that it is sunnah to drink what is left over by another person in his glass. How could this be explained in the light of the fact that certain diseases can be transmitted this way?

A182 : It is certainly not a sunnah to drink what someone else has left over in his glass. When we say that it is a sunnah, it means that Islam recommends it. To have such a recommendation, we need to have some sort of instructions by the Prophet. There is none in this particular case. But we have to understand that in such a situation it is not sufficient that the Prophet had shared the same glass or cup with other people. In order to make sure that we know what he has recommended, he would have followed that with a verbal statement of some sort. The absence of any, means that it is not a sunnah. It is true that we have some reports which tell us that the Prophet was offered some drink when there were so many people. There was little amount of that drink in the container. The Prophet drank from it and passed it over to the person sitting next to him. He drank his fill and passed it over again. The same was repeated over and over again until everyone drank as much as he wanted. But that was a special case and one of many incidents in the life of the Prophet which Allah facilitated in order to reassure those early Muslims that they were following the true religion taught by the Messenger of Allah who always spoke the truth. As you say, certain diseases could be transmitted through such a practice, which means, by necessity, that it could not be recommended by Islam.

Our Dialogue ( Source : Arab News - Jeddah )