What is the ruling on trimming the beard if it exceeds a fistful?

The Prophet's Sunnah regarding letting the beard grow is both verbal and practical. He commanded that it be left, made full, and abundant, in order to differentiate from the polytheists and the Zoroastrians. It has not been authentically reported that the Prophet, peace and blessings be upon him, ever trimmed his beard. As for the narration that the Prophet, peace and blessings be upon him, trimmed his beard from its width and length, it is weak and not authentic. Trimming the beard or taking anything from its length or width is impermissible, as it contradicts the command of the Messenger of Allah, peace and blessings be upon him. Some scholars have permitted trimming what exceeds a fistful, citing the action of Ibn 'Umar, but Ibn 'Umar's opinion is not a proof superseding the Prophetic Sunnah, and the majority view is to leave the beard as it is without shortening it.