إني أراك تقدم رجلاً وتؤخر أخرى
I see you setting one foot forward and drawing the other back.
Applied to an indecisive person, the description is not confined to actual leg movements. The source is a person exhibiting an alternating pattern of physical advance and retreat; the target is someone whose intention and decision are similarly divided.
The contextual clue is the person’s actual indecision, while the shared resemblance is the conflict of contrary tendencies within a single pattern of conduct. The sentence may be literally true in its original context; the figurative classification attaches to its new use.