Assalamo alaikum,I heard ages before that the one who makes fun of beard, is expelled from islam or given any other grave penalty. Is this true?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad, sallallaahu`alayhi wa sallam, is His slave and Messenger.

There is no doubt that the Muslim is enjoined by Sharee'ah to let his beard grow, but there is a difference between mocking the beard because it is from the Sunnah and the guidance of the Prophet, sallallaahu`alayhi wa sallam, and mocking some of the bearded people themselves. So mockery or ridicule, if it is intended to make fun of the shape of the beard of someone, such as because of being unkempt, and he did not intend to mock its legitimacy, then this mockery is forbidden because Allah The Exalted says (what means): {O you who have believed, let not a people ridicule [another] people; perhaps they may be better than them...} [Quran 49:11]

This prohibition does not amount to disbelief, but if ridicule and mockery are at the root of its legitimacy because it is from the Sunnah of the Prophet, sallallaahu`alayhi wa sallam, then there is no doubt that the matter is dangerous and there is fear that the perpetrator would fall into disbelief because it is a mockery of what Allah Almighty has ordained. Shaykh Ibn Baz was asked: Is there anyone who mocks the religion by making fun of the beard, or the shortening of the clothes, is it considered disbelief? He replied: This differs if his intention was to mock the religion, then it is disbelief, as Allah The Exalted says (what means): {And if you ask them, they will surely say, "We were only conversing and playing." Say, "Is it Allah and His verses and His Messenger that you were mocking?" Make no excuse; you have disbelieved after your belief. If We pardon one faction of you - We will punish another faction because they were criminals.} [Quran 9:65-66]

Thus if his intention is to make fun of religion, and belittle religion, then it is disbelief. We seek refuge in Allah. He (Shaykh Ibn Baz ) was asked: “If he used to say: I say that to people just for joking?” He replied: This is not permissible, and this is reprehensible and its perpetrator is in danger, and if his intention is to mock the religion, then it is disbelief.

Allah knows best.