This prophecy had two fulfillments, each complementary to the other. Manasseh, Hezekiah’s actual son, was “carried to Babylon” 2 Chronicles 33:11, but did not become a eunuch in the palace. Daniel and others, not his actual sons, but of the royal seed Daniel 1:3, and therefore Hezekiah’s descendants, are thought by some to have literally fulfilled the latter part of the prophecy, being eunuchs in the palace of Nebuchadnezzar.
Related Commentaries of 2 Kings 20:18
2 Kings 20:18
18 And of thy sons that shall issue from thee, which thou shalt beget, shall they take away; and they shall be eunuchs in the palace of the king of Babylon.