No! I swear by the Lord of the Easts and Wests that We have the power. (Qur'an, 70:40)
Lord of the heavens and the earth and everything between them; Lord of the Easts. (Qur'an, 37:5)
The Lord of the two Easts and the Lord of the two Wests. (Qur'an, 55:17)
As can be discerned, the words east and west are used in the plural sense in the above verses. For instance, the word "mashariq," used in the first verse for "east," and the word "magharib" used for "west," are in plural form, indicating that there are two of each. The words "mashriqayn" and "maghribayn" in the last verse are used for two easts and two wests. "Mashariq" and "magharib" also mean the place where the Sun rises and sets. The above verses are therefore referring to different sites of the dawning and closing of the day. It is also worthy of note that the vow is taken by the Lord of "the easts and wests" in the first verse.
The axis around which the earth revolves itself is at an angle of 23° 27'. Due to that angle, and the spherical shape of the Earth, the light rays from the Sun do not always strike it at the same angle. This means that since the Sun's rays fall on that area at different angles, someone far away from the equator will observe the Sun rising at different points in the east and setting at different points in the west. The further away from the equator that person is the more different points he will identify for the dawning and closing of the day.
Someone at the equator, however, will always observe that the Sun rises exactly in the east and sets exactly in the west, since the Sun's rays always fall perpendicularly there. Bearing in mind that the Arabian peninsula is not that far from the equator, it would appear impossible for such an observation to be made there. That is because someone in that region would see that the Sun always rises at the same point, and always sets at the same point. The expression regarding east and west in the above verses may be indicating the Sun rising and setting at different points. (Allah knows best.)