Places Where Prayer is Permissible and Where it is Not Permissible

Ali ibn Mahziyar asked Abu Al-Hasan the Third, Imam Ali ibn Muhammad Al-Hadi عليه السلام, about a man who finds himself in the desert (al-Bayda') when the time for an obligatory prayer comes and does not leave the desert until the prayer's time has passed. He asked: "What should he do about the prayer, given that it is prohibited to pray in al-Bayda'?" Imam عليه السلام said: "He should pray there, but he should avoid the main path (road)."