‘Therefore with joy will you draw water out of the wells of salvation.'
Isaiah adds his comment to the song, and speaks to all. ‘You' is here in the plural. Because of their wonderful deliverance they can all come continually to draw water from the wells of salvation. The spring-fed well was the basis of life for the Israelites. It was alongside wells that they built their cities. From wells they irrigated their crops. And now their saving God has provided a continual spring, welling up abundantly, from which to finalise what He has begun, so that as they live day by day with God they can continue drinking from the abundance of that spring (compare John 4:13-14).