Are there any scriptural texts threatening those who speak about Allah without knowledge?

Speaking about Allah without knowledge is among the greatest major sins and most heinous transgressions. Allah has equated it with shirk (associating partners with Him) and threatened severe punishment for it, as stated in His verse: "Say, 'My Lord has only forbidden immoralities—what is apparent of them and what is concealed—and sin, and oppression without right, and that you associate with Allah that for which He has not sent down authority, and that you say about Allah what you do not know.'" (Al-A'raf: 33). Ibn al-Qayyim affirms that speaking about Allah without knowledge is the most forbidden of all prohibitions and the greatest in sin, as it entails lying about Allah and altering His religion. It is the root of shirk and disbelief, and the foundation of innovations (bid'ah) and misguidance.