What is "b'His'halechecha"?
Rashi (from Sotah 21a): In your lifetime.
Malbim: It is when you go on the road. Our verse parallels going on the road, lying down and rising, mentioned above (3:23-25). There is danger on the road; [Torah] will guide you in the straight path.
What is the meaning of "Tancheh Osach"?
Rashi: This is like Tanhigecha (it will lead you). This is in this world (Sotah 21a).
Ma'alos ha'Torah: Torah saves him from all mishaps, in this world and in the next.
When is "b'Shachbecha"?
Rashi (from Sotah 21a): It is in the grave.
Malbim: It is when you lie down. There is danger, for he does not use his senses and Sechel at the time; [Torah] will guard you.
When is "va'Hakitzosa"?
Rashi (from Sotah 21a): It is standing in judgment at [the time of] Techiyas ha'Mesim.
Malbim: It is when you rise.
How will Torah be "Tesichecha"?
Rashi (from Sotah 21a): It will advocate for you.
Malbim: It will be your conversation.