DRINKING WATER AND THE SHAITAAN
Once when Rasulullah (sallallahu alayhi wasallam) saw a man standing while drinking water, he rebuked the man. The man asked what error he had committed. Rasulullah (sallallahu alayhi wasallam) said: “Would you like a cat to drink with you?” The man said: “No.” Rasulullah (sallallahu alayhi wasallam) said: “Someone worse than a cat was drinking with you, namely, the shaitaan.”
According to Imaam Shaafi' (rahmatullah alayh), even when drinking Zam Zam water one should sit. The Mashaaikh also warn of sicknesses developing when a person drinks water standing.