Matthew Poole and continuators on Isaiah 30:21

21. And thine-ears shall hear a word behind thee , saying, This is the way, walk ye in it, when ye turn to the right hand, and when ye turn to the left.

As oft as need requires thou shalt hear the voice of God's Word and Spirit directing thee in thy Course.

A Metaphor borrowed either 1. from the custom of Shepherds, who use to follow their Sheep, and to recall them when they go out of the way. Or 2. from Travellers, who, when they are gone out of the right way, are oft-times recalled and admonished of their Errour, by some other Passenger or Person, who is behind them, and therefore discerns their mistake; which he could not so easily discover, if he were before them.

Marginal references: Josh. 1. 7.