Daniel 4:33 (BSB)

At that moment the sentence against Nebuchadnezzar was fulfilled. He was driven away from mankind. He ate grass like an ox, and his body was drenched with the dew of heaven, until his hair grew like the feathers of an eagle and his nails like the claws of a bird.

From Daniel 4. Also in the ESV.

Commentary on Daniel 4:33

John Calvin (Reformed), Calvin's Commentaries on Daniel 4:33: The Prophet concludes what he had said: As soon as the voice had come down from heaven, Nebuchadnezzar was cast out from mankind! Some occasion of expelling him might have preceded this; but since the divination is uncertain, I had rather leave undetermined what the Holy Spirit has not revealed.
Matthew Henry (Presbyterian), Matthew Henry's Complete Commentary on Daniel 4:28-33: We have here Nebuchadnezzar's dream accomplished, and Daniel's application of it to him justified and confirmed. How he took it we are not told, whether he was pleased with Daniel or displeased; but here we have, I. God's patience with him: All this came upon him, but not till twelve months after (Dan 4:29), so long there was a lengthening of his tranquility, though it...
John Gill (Reformed Baptist), Exposition of the Old and New Testaments on Daniel 4:33: At the same time my reason returned unto me,.... Or, "my understanding" (q); this he repeats, not only to express the certainty of it, but the sense he had of the greatness of the favour, and of which what he said at this time is a full proof: and for the glory of my kingdom mine honour and brightness returned unto me: or "form" (r)...
Jamieson-Fausset-Brown (Reformed), Commentary Critical and Explanatory on the Whole Bible on Daniel 4:33: driven from men--as a maniac fancying himself a wild beast. It is possible, a conspiracy of his nobles may have co-operated towards his having been "driven" forth as an outcast. hairs . . . eagles' feathers--matted together, as the hair-like, thick plumage of the ossifraga eagle. The "nails," by being left uncut for years, would become like "claws."