John Gill Commentary Zechariah 8:13

"And it shall come to pass that, as ye were a curse among the nations, O house of Judah and house of Israel, so will I save you, and ye shall be a blessing. Fear not, [but] let your hands be strong." — Zechariah 8:13 (ASV)

And it shall come to pass, [that] as you were a curse among
the heathen
Reproached, vilified, and called accursed by them; see (Jeremiah 24:9) as true Christians, and real believers in Christ, are by the men of this world, (1 Corinthians 4:12 1 Corinthians 4:13) :

O house of Judah, and house of Israel ;
both being carried captive at different times, and were typical of the true and Spiritual Israel of God:

so will I save you, and you shall be a blessing ;
be blessed in themselves with the above blessings of plenty and prosperity in outward things; see (Haggai 2:19) and a blessing to others, and blessed by them; and all those who are saved in the Lord with an everlasting salvation are blessed with all spiritual blessings in him:

fear not ;
neither their enemies, nor the accomplishment of these promises:

[but] let your hands be strong ;
as in (Zechariah 8:9) .