This day will I begin to magnify thee - One cause why the miracle now to be narrated was performed is here suggested. As Moses was declared to he sent immediately from God with an extraordinary commission by the miracles which he worked, more especially that of dividing the Red Sea in two parts, so was Joshua both sent and accredited in a like manner. (Compare Joshua 1:5, and Joshua 4:14.) Other reasons are given in Joshua 3:10; Joshua 5:1.
Related Commentaries of Joshua 3:7
Joshua 3:7
7 And the LORD said unto Joshua, This day will I begin to magnify thee in the sight of all Israel, that they may know that, as I was with Moses, so I will be with thee.