This is a very cool little hymn I found in Vol. 48 of Analecta hymnica medii aevi, p. 303. There's a first verse for St. Isaiah, another for St. Daniel, and a generic prophet verse. It's to the tune of "A solis ortus cardine", so that makes it very quick to learn. (On the next page, there's a hymn structured the same way for St. Isaac and St. Jacob to the tune of "Aeterne rex altissime", but that's not quite so easy to get.)

Since the feast (or optional memorial, or whatever) of St. Daniel the Prophet is tomorrow, July 21, I thought I'd post it. (Sorry English translation by me.)

Isaiah verse:

Ave, certum praesagium
Ferens de partu virginis
Dicendo: Ecce, numinis
Virgo pariet filium.

Hail, sure prediction
Telling of the virgin birth,
Saying, “Behold! of the divine
The virgin will bring forth a son.”

Daniel verse:

Ave, cuius vox conterit
Iudaeos hoc praesagio:
Cum sanctorum advenerit
Sanctus, cessabit unctio.

Hail, Whose voice breaks [kingdoms]
With this prediction to the Jews.
When the saint comes with the saints,
[His] anointing will rest.

Generic verse:

O prophetarum contio
Certo vigens praesagio,
Exora voce sedula
Pro me regentem saecula.

O speech of the prophets!
Active, sure prediction,
Win me, o careful voice,
Directing me for ages.