What is the ruling on drinking water while standing, and what is the validity of some people's argument, based on the action of Ali ibn Abi Talib (may Allah be pleased with him) who drank while standing, and on the Prophet's (peace be upon him) command to dye hair, that the command does not imply obligation?

The Prophet, peace and blessings be upon him, forbade drinking while standing and also drank while standing to show that it is permissible. These two actions have been reconciled by understanding that the prohibition implies a disliking (tanzih), not a prohibition (tahrim). As for the command to dye hair with a color other than black, it is not obligatory. The difference among the Salaf regarding the command and prohibition of changing hair color stems from the different circumstances they faced.