Does a Muslim apostatize if he utters a person's name instead of Allah's name in the phrase "I worship none but Allah," while in a state between wakefulness and sleep, knowing that he intended to mention Allah's name but his tongue slipped, and he immediately rectified the matter by mentioning Allah's name thereafter?

Apostasy does not occur due to what you mentioned, because a word uttered by someone who is absent-minded or whose tongue slipped unintentionally does not entail a ruling. Strive to rid yourself of obsessive whispers, and occupy your mind away from them with knowledge, inviting to Allah, and reading the stories of the prophets and the predecessors. When obsessive whispers come, seek refuge in Allah and say: "I believe in Allah and His messengers."