There is the habit of some people in which when they eat and want to drink after, they pick up the glass with their left hand and place the back of their right hand underneath the glass. Is this legislated in the sunnah?
Some of the shuyookh say if the majority of his left hand is on the glass, and it being more than how much his right hand is on the glass when drinking, then it is haraam. And if the majority of his right hand is on the glass and he is just using his left hand for support, then it is permissible. And if both hands are equally balanced, then it is a doubtful matter which should be avoided. And some shuyookh of yemen say here (in this case) it is built upon his intention, on which he intends to drink with.
In all cases, most people do so just so they don’t get the cup dirty while in fact they will eventually have to wash it. So, they should just hold it with their right hand and Allah knows best.
AbdulFattaah bin Uthman