a note i found.
Isaiah 9:3
Thou hast multiplied the nation
With light, knowledge, honour, and glory, even Galilee of the nations before mentioned, the land of darkness, and of the shadow of death, where the people dwelt; on whom Christ, the light, shone in the ministration of his Gospel to them; whereby the number of believers in Christ were multiplied; and indeed, as he conversed, preached, and wrought his miracles most here, he had here the greatest number of disciples and followers; here were the five hundred brethren by whom he was seen at once, after his resurrection, ( 1 Corinthians 15:6 ) ( Matthew 28:7 Matthew 28:10 Matthew 28:16 ) for this is not to be understood of the Assyrian nation, whose army under Sennacherib was very large; nor of the Jewish nation enlarged by the destruction of that army, or of their increase after their return from the Babylonish captivity; nor of the church of God by the accession of Gentiles to it; but of the land or nation before spoken of: [and] not increased the joy;
or rather, as it should be rendered, "and hast increased joy unto it"; following the Keri; or marginal reading, which directs that it should be read, not as a negative, (al) "not", but (wl) , "to it"; and which is followed by the Targum and Syriac version, and by Jarchi, Aben Ezra, and Kimchi, and others; and the sense of the words requires this reading, since it follows, they joy before thee;
or otherwise there would be a manifest contradiction in the text; though some, to avoid it, read the words interrogatively, "hast thou not increased the joy?" thou hast; and in this way both the Keri and the Cetib, the reading and the writing, may be taken in, "hast thou not increased joy unto it?" and so as Gussetius