From thence — i.e., away from thence, meaning, as soon as she has left the wilderness of exile and discipline. The valley of Achor (or trouble) was associated with the disgrace and punishment which befel Israel on her first entrance into Palestine (Joshua 7:25-26), but it would in later days be regarded as the threshold of a blessed life. The sorrowful associations of the past were to be illuminated with happy anticipation.
Sing may suggest a reference to the dances and responsive songs at the village festivals, as well as to the triumphant strains of Exodus 15