Qur'anic verses - The Apostle:

Years after the mission of Prophet Hud to the Southern people of the Arabian Peninsula, another transgression was repeated at the other edge of the wide Peninsula. God would not leave the people without guidance and to every people He sent an apostle; God said:

To every people (was sent) an Apostle.
[Qur'an 10:47]

Salih was God's apostle to his own people, Thamud, who dwelled the Western Northern region of the Arabian Peninsula, to re-establish the true monotheism faith and retain its purity; God said:

To the Thamud people (We sent) Salih, one of their own brethren: he said: "O my people! worship God! ye have no other god but Him."
[Qur'an 7:73]