"He alone of all the prophets"

Dieric Bouts I (c. 1415-1475),
Ecce Agnus Dei (1464/66),
Alte Pinakothek, Munich

"He alone of all the prophets pointed out the Lamb of redemption."

"ipse solus omnium prophetarum Agnum redemptionis ostendit."

     Preface for the Solemnity of the Nativity of John the Baptist, Roman missal.
     As the sources make clear, the emphasis here should be on "pointed out" (ostendit).  John's predecessors, too, foretold (praenuntiavit) his coming, but only John was in a position to point to an individual present in flesh and blood and say, "Behold, the Lamb of God".  "Leonine" (i.e. Veronese) sacramentary no. 254, Supplement (Supplementum Anianense) to the Gregorian sacramentary no. 1630, and so forth:

solusque omnium prophetarum redemptorem mundi quem praenuntiavit ostentit.

and alone of all the prophets pointed out the redeemer of the world whom he foretold.

See Ward and Johnson, The prefaces of the Roman missal:  a source compendium with concordances and indices (Rome:  Congregation for Divine Worship, 1989):  420-421.  See also Corpus praefationum no. 464, and especially on pp. 221-222 of the first volume of the Apparatus, where those earliest sacramentaries (and more) are referenced, but the profound enrichment this Preface has undergone since is noted:  "the Leonine and Gelasian original has been here profoundly recast and enriched" (222).
     On pp. LXXIV and LXXXII of his critical edition of the "Leonine" or Veronese sacramentary, Mohlberg, citing p. 115 of vol. 1 (1948) of Bourque's Étude sur les sacramentaires romains, traces this to the layer of that sacramentary dated 468-c. 500 (or the early 6th century).
     If I'm not mistaken, the pre-1962 missal made no use of this Preface.