Abbas - Tanwîr al-Miqbâs min Tafsîr Ibn ‘Abbâs
(And unto (the tribe of) Thamud) and We sent to Thamud (their brother) their Prophet (Salih. He said: O my people! Serve Allah) declare the divine Oneness of Allah, (You have no other God save Him) you have no god except the One in Whom I command you to believe. (He brought you forth from the earth) He created you from Adam and Adam is from the earth (and hath made you husband it) He made you thrive in the earth and made its inhabitants thrive on it too. (So ask forgiveness of Him) confess His divine Oneness (and turn unto Him repentant) turn to Him by believing in His divine Oneness, repenting and being sincere to Him. (Lo, my Lord is Nigh) in His answer, (Responsive) to the one who declares His divine Oneness.
And, We sent, to Thamūd their brother, from the tribe, Sālih. He said, ‘O my people, worship God!, affirm His Oneness. You have no god other than He. He it is Who produced you, [Who] began your creation, from the earth, by creating your father Adam from it, and has given you to live therein, He has made you inhabitants, living therein; so ask forgiveness of Him, from idolatry, then turn, return, to Him repentant, through [acts of] obedience. Truly my Lord is Near, to His creation by [virtue of] His knowledge, Responsive’, to those who ask of Him.
(And when My servants ask you concerning Me, then (answer them), I am indeed Near (to them by My knowledge). I respond to the invocations of the supplicant when he calls on Me.) 2:186
Maududi - Sayyid Abul Ala Maududi - Tafhim al-Qur'an
Please keep in view E.N.'s 57-62 of Al-A'Aaraf.
This is the proof of the claim: ".... you have no other Deity than Allah".The argument is based on the fact which the mushriks themselves acknowledged that it is Allah Who is their Creator. Therefore Prophet Salih argued like this: "You yourselves acknowledge that it is Allah Who has created your wonderful human body out of the life-less particles of the earth and that it is Allah Who has made the earth a suitable place for you to live. How can then there be any Deity other than Allah Who may be worthy of Godhead, service and worship?"
That is, "So ask His forgiveness for the sin you have been committing by worshiping others."
In this concise sentence, the Qur'an has refuted a grave misunderstanding of the mushriks, which has in every age misled people into wrong creeds. They presumed that Allah lived far away from them and, therefore, was unapproachable like their own rulers on the earth. As the only way of approach to them was an intercessor who alone could receive and present their requests and applications to their rulers, and convey their answers to them, they presumed that there should be some intercessor to help approach Allah and bring to them the answers to their prayers. Obviously this is a false presumption, which has been endorsed and encouraged by clever people that Allah is out of the reach of common people and it is not possible for them to reach Him and present their prayers and get their answers. So they should search for such sacred beings as may have an approach to Him. Accordingly, they tried to secure the services of those who were well-versed in the art of conveying the requests with the necessary presents and gifts to the Highest Authority. This misunderstanding created hosts of intercessors, and the establishment of the system of priesthood, which has so incapacitated the followers of mushrik creeds of ignorance that they cannot perform by themselves any religious ceremony from birth to death.
Now let us consider the concise answer of Prophet Salih, by which he broke asunder the false presumption of the mushriks. It is this: "Allah is near at hand: so you can invoke His help directly without the help of any interceder. He answers prayers: so you can yourselves receive the answer to your prayer. Though He is the Highest, each one of you will find Him so near yourself that you will be able to convey your request even in a whisper, nay, you are permitted to convey your requests openly or secretly to Him. Therefore give up the folly of seeking interceders and setting them up as His partners, and address your prayers to Him Who is near at hand and answers prayers." (Please refer also to E.N. 188 of Al-Baqarah. )