25 And he set the Levites in the house of Yahweh with cymbals, with psalteries, and with harps, according to the commandment of David, and of Gad the king's seer, and Nathan the prophet: for so was the commandment of Yahweh by his prophets.

The prophet was also called a seer (both terms are sometimes used in the same sentence—Isaiah 30:10; 2 Chron. 29:25). The term "seer" (chozeh, from the verb to see) expressed the fact that a man whose eyes God opened saw things unknown to normal human faculty (Num. 24:3–4).

The term prophet (nabah) from the Hebrew verb to flow forth, intimated that a man so illuminated could not repress the ideas afflating him, as in the case of the men in the house of Cornelius, upon whom the Holy Spirit having been poured out, all heard them speak with tongues (Acts 10:45–46).

...The popular idea that the prophets began with Isaiah and ended with Malachi is due to the mere arrangement of those prophetic books that have been preserved. The names of the prophets between Isaiah and Malachi represent but the merest fraction of the prophets that arose—a very important fraction to us, certainly—the most important that could be imagined; for without the books of these prophets, our knowledge of the mind of God as expressed through the prophets would be scanty to the famine point.

Ministry of the prophets Ch 2