Prophecy of Isaiah (2:4). Inscription reads as follows: IUDICABIT GENTES, ET ARGUET POPULOS MULTOS, ET CONFLABUNT GLADIOS SUOS IN UOMERES, ET LANCEAS SUAS IN FALCES. ISAIAE II (And he shall judge among the nations, and shall rebuke many people: and they shall beat their swords into plowshares, and their spears into pruninghooks." Also inscribed between the legs of the putto: PAX. On ground near flower basket at right: FOELICITAS. On the cross, PIETAS. On the cornucopia, ABUNDANTIA.
The figure of Isaiah is in center; Peace is burning a helmet over a fire and holding an olive branch. At forge figures are plunging swords into plowshares. The Female figures at right are fruits of peace: Felicity, Piety and Abundance.

Painting was probably either commissioned by or given to Maximilian I of Bavaria, leader of Catholic League, as reference to conclusion of twelve-years truce in 1609. He also owned Jan's Jonah and the Whale now in Munich.
Neumeister in Munich 2013 (p.273, note 10) believes that the figures around the smithy are also by Van Balen, which seems odd given that this was a subject that Jan had already painted on his own before this (a smithy, not Isaiah); she says that one can tell this from the manner of painting the flesh but I cannot see this at all.
The infrared published there shows that the figures were originally conceived as being quite a lot larger. Probably the theme of the picture was originally a "Venus at the Forge of Vulcan" and it was changed around to accommodate the Isaiah theme for this 1609 commission; hence the work could have been begun slightly earlier.