Khalid bin 'Abdullah al-Tahan خالد بن عبد الله بن عبد الرحمن الطحان · The Book of the Prayer

The Prophet said: "Do not let the Bedouins make you change the name of your prayer." Ibn Harmalah added: "Rather it is the 'Isha', but they say the 'Atamah because they bring their camels in for milking at that time (when it is dark)."