An-Nisa 4:101

Wa-itha darabtum fee al-ardifalaysa AAalaykum junahun an taqsuroo mina assalatiin khiftum an yaftinakumu allatheena kafaroo inna alkafireenakanoo lakum AAaduwwan mubeena

And when you travel throughout the land, there is no blame upon you for shortening the prayer, [especially] if you fear that those who disbelieve may disrupt [or attack] you. Indeed, the disbelievers are ever to you a clear enemy.

When you travel on the earth, there is no sin on you in shortening your Salāh, if you fear that the disbelievers would put you in trouble. Surely, the disbelievers are an open enemy for you.