Is shaving the beard forbidden (haram), and will the one who does so be punished in the Hellfire?

Shaving the beard is definitively forbidden due to it contradicting the Prophet's (peace be upon him) command to let it grow. Al-Bukhari and Muslim narrated: "Trim the mustaches and let the beards grow; be different from the polytheists." Muslim and Ahmad narrated: "Trim the mustaches and let the beards hang; be different from the Magi." Ibn Sa'd also mentioned that the Prophet (peace be upon him) saw a Magian who had let his mustache grow and trimmed his beard, so he asked him: "Who commanded you to do this?" The Magian replied: "My lord." The Prophet (peace be upon him) then said: "But my Lord commanded me to trim my mustache and let my beard grow."

Do not look at the smallness of the sin, but rather at the greatness of the One Whom you have disobeyed. Persistent small sins turn into major sins and may lead their perpetrator to ruin, as the Prophet (peace be upon him) said: "Beware of trivial sins, for the similitude of trivial sins is like people who settled in the bottom of a valley. One brought a stick, and another brought a stick, until they gathered enough to cook their bread. And indeed, trivial sins, when they are taken account of, will destroy their perpetrator." And his (peace be upon him) saying to 'Aisha: "O 'Aisha, beware of trivial sins, for they have an accuser from Allah."

Therefore, shaving the beard is a sin that should not be underestimated, and Allah dislikes all sins, whether small or large.