Is growing the beard a confirmed Sunnah so that whoever shaves it is sinful; and what is the evidence? What is the difference between a Sunnah and a confirmed Sunnah?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

A confirmed Sunnah and a non-confirmed Sunnah are within the boundaries of recommended matters. Meaning that whoever does it is rewarded and whoever leaves it, is not sinful. Nonetheless, a confirmed Sunnah is more recommended to be done. The author of Al-Kawkab Al-Muneer said: “What is recommended in religion is something for which the doer is rewarded, like the supererogatory prayers, even if it is only a statement one utters, like the mention of Allaah said during Hajj, or an act of the heart like being humble when performing the prayer, and the one who does not perform such recommended acts is not punished. What is permissible is also called Sunnah, something desirable, voluntary, an act of obedience, a supererogatory act, an action by which one gets closer to Allaah, something urged, and something good.”

As regards the ruling of growing the beard, please refer to Fatwa 84475. 

Allaah Knows best.