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)." (Using translation from Ibn Mājah 705)   

عَنِ النَّبِيِّ ﷺ قَالَ لَا يَغْلِبَنَّكُمْ الْأَعْرَابُ عَلَى اسْمِ صَلَاتِكُمْ فَإِنَّهَا الْعِشَاءُ إِنَّمَا يَدْعُونَهَا الْعَتَمَةَ لِإِعْتَامِهِمْ بِالْإِبِلِ لِحِلَابِهَا  

[Machine] "From the Prophet ﷺ , the Arabs should not overpower you with the pronunciation of your prayers, as they are recorded in the Book of Allah. They refer to the evening prayer as 'al-Isha', but the Arabs named it 'al-A'tamah' due to their camels returning to their pens."  

عَنِ النَّبِيِّ ﷺ لَا يَغْلِبَنَّكُمُ الْأَعْرَابُ مِنِ اسْمِ صَلَاتِكُمْ فَإِنَّهَا فِي كِتَابِ اللهِ ﷻُّ الْعِشَاءُ وَإِنَّمَا سَمَّتْهَا الْأَعْرَابُ الْعَتَمَةُ مِنْ أَجْلِ أَبِلِهَا لِحِلَابِهَا  

"لا تَغْلِبَنَّكُمُ الأَعْرَابُ عَلَى اسْمِ صَلاتِكُمْ، فَإنَّما هِيَ الْعِشَاءُ، وَإنَّما يَقُولُون: الْعَتَمةُ لإِعْتَامِهِم بالإِبِلِ".  

"لا تَغْلبَنَّكُمُ الأَعْرَابُ عَنِ اسْمِ صَلاتِكُمْ، فَإِنَّها فِي كِتَابِ اللهِ الْعِشَاءُ، وَإِنَّما سَمَّتْهَا الأَعْرَابُ الْعَتَمَةَ مِنْ أَجْلِ إِبِلِهَا لِحِلابِهَا".