Surah 91. Ash-Shams, Ayah 15

Implying that their total lack of compassion for God's creatures showed that they did not fear His retribution and, hence, did not really believe in Him.

This verse has been variously construed. I follow the general opinion in referring the pronoun "Him" to "their Lord" in the last verse and the pronoun "its" to the Punishment that was meted out to all, high and low, equally. In that case the meaning would be: God decreed the total destruction of the Thamud; in the case of creatures any such destruction might cause a loss to them, and they might fear the consequences of such loss or destruction, but Allah has created and can create at will, and there can be no question of any such apprehension in His case. An alternative view is that "him" refers to the prophet Salih, mentioned in verse 13. Then the interpretation would be: Salih had no fear of the consequences for himself; he had warned the wicked according to his commission; he was saved by Allah's mercy as a just and righteous man, and he left them with regrets (vii. 79). Yet another alternative refers "him" to the wicked man (mentioned in verse 12) who hamstrung the she-camel: he feared not the consequences of his deed.