Hazrat Mujahid says that "Shafaq" is the name of the remaining part of the day.

Hazrat Ja'far bin Burqan says that Hazrat Umar bin Abdul Aziz wrote a letter to us stating that perform the Maghrib prayer at the time when the fasting person breaks his fast. Then he said that there are some people with me who perform the Isha prayer before the whiteness of the horizon disappears. Do not perform the Isha prayer until the whiteness of the horizon in the west has disappeared and until the darkness of the night has spread. The longer you delay after the whiteness of the horizon in the west has disappeared, the better it is. Know that the best and actual time for prayer is the one I have mentioned in my letter, that is, the time after the whiteness of the horizon has disappeared, because the real time for the end of the day is this.

Hazrat Abu Huraira says that when the twilight disappears and night falls, then perform the Isha prayer before one third of the night has passed. The more you delay after the whiteness disappears from the horizon, the better it is.

Hazrat Hanzala narrates that Hazrat Tawus used to perform the Isha prayer before the whiteness of twilight disappeared.

Hazrat Ikrimah says that "shafaq" is the name of the remaining part of the day.