و من كتاب له عليه السلام إلى أمراء البلاد في معنى الصلاة
اما بعد فصلوا بالناس الظهر حتى تفی الشمس مثل مربض العنز و صلوا بهم العصر و الشمس بیضا حیه فی عضو من النهار حین یسار فیها فرسخان و صلوا بهم المغرب حین یفطر الصائم و یدفع الحاج (الى منى) و صلوا بهم العشا حین یتوارى الشفق الى ثلث اللیل و صلوا بهم الغداه و الرجل یعرف وجه صاحبه و صلوا بهم صلاه اضعفهم و لا تکونوا فتانین
A Letter from Imam Ali (a.s)
[A circular about prayers to the governors of all the provinces.]
Lead the Zuhr prayer till the shadow of a wall becomes equal to the height of the wall, the Asr prayers can be performed till the sun is still bright and enough time of the day is left for a person to cover a distance of six miles. The Maghrib prayers should be performed when people break their fasts and when Hajj pilgrims return from Arafat. And the time for Ice prayers is when the red glow of the even twilight disappears from the West, till one-third of the night is still left. The morning prayers are to be performed when there appears enough light of the dawn for a man to recognize the face of his companion.
While leading the prayers make them so short that the weakest among you may not feel tired to follow you and his strength and patience may not be over strained.