Al-An'am: 165
{He it is who made you successors upon the earth}
Because Muhammad (peace be upon him) is the Seal of the Prophets, his nation has succeeded all other nations. Or, it means He made them succeed one another. Or, they are God’s deputies on His earth, possessing it and exercising authority within it.
{And raised some of you above others in degrees}
In honor and provision.
{To test you in what He has given you}
Of the blessings of wealth and status: how you show gratitude for that blessing, and how the noble treats the lowly, the free person treats the slave, and the rich treats the poor.
{Indeed, your Lord is swift in punishment}
For those who deny His blessings.
{And indeed, He is Forgiving, Merciful}
For those who stand to show gratitude for them. He described the punishment as "swift" because whatever is coming is near.
From the Messenger of God (peace be upon him):
"Surat al-An'am was revealed to me all at once, accompanied by seventy thousand angels, their voices raised in glorification and praise. Whoever recites al-An'am, those seventy thousand angels will pray for him and seek forgiveness for him, for every verse in Surat al-An'am, for a day and a night."