C. F. Keil and Franz Delitzsch on Isaiah 41:3

Isa 41:3

The conqueror is now still further described in futures, which might be defined by העיר, and so express a simultaneous past (synchronistic imperfects), but which it is safer to take as standing traits in the picture drawn of the conqueror referred to. “He pursueth them and marcheth in peace by a course which he never trod with his feet.” He marches victoriously further and further, shâlōm,” i.e., “in safety” (or, as an adjective, safely; Job 21:9), without any one being able to do him harm, by a course (accus. Ges. §138, 1) which he has not been accustomed to tread with his feet (ingredi).