Sunan Ibn Majah
705
Hasan Sahih+2

It was narrated from Abu Hurairah that: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)

Hasan SahihAl-Albani
Hasan SahihMuhammad Fouad Abd al-Baqi