Hud 84

Allah, the Exalted, says, `We sent a Messenger to the people of Madyan.’ They were a tribe of Arabs who lived between the land of the Al-Hijaz and Ash-Sham, close to the land of Ma`an. Their land was known by the name of their tribe and was thus, called Madyan. Allah sent unto them the Prophet Shu`ayb and he was of the noblest of them in lineage. For this reason, Allah said,

their brother Shu`ayb

Shu`ayb commanded them to worship Allah alone without associating any partners with him. He also prohibited them from cheating in their weights and measures (for business transactions).

I see you in prosperity

meaning, `in your livelihood and your provisions. And verily, I fear that you will be deprived of this bounty that you are enjoying by violating Allah’s prohibitions.’

and verily, I fear for you the torment of a Day encompassing

This means the abode of the Hereafter.