Albert Barnes Commentary Isaiah 54:4

"Fear not; for thou shalt not be ashamed: neither be thou confounded; for thou shalt not be put to shame: for thou shalt forget the shame of thy youth; and the reproach of thy widowhood shalt thou remember no more." — Isaiah 54:4 (ASV)

Fear not ... - (See notes on Isaiah 41:10 and Isaiah 41:14).

Neither shall you be confounded - All these words mean substantially the same thing; and the prophet's design is to affirm, in the strongest possible manner, that the church of God will be abundantly prospered and enlarged. The image of the barren female is kept up, and the idea is that there will be no occasion for the shame that a childless woman felt.

For you shall forget the shame of your youth - In the abundant increase and glory of future times, the circumstances of shame that attended their early history will be forgotten. The 'youth' of the Jewish people doubtless refers to the bondage of Egypt, and the trials and calamities that came upon them there. So great will their future prosperity and glory be, that all this will be forgotten.

The reproach of your widowhood - The captivity at Babylon, when they were like a woman deprived of her husband and children (see the notes on Isaiah 49:21).