Allah says: `say, O Muhammad, to these people who disbelieve the Message you have brought: travel in the land and see what was the punishment of those who disbelieved the Messengers, how Allah destroyed them completely, and a similar (end awaits) the disbelievers. See how their homes were emptied of them and how they lost everything after living in luxury and being so numerous and so well equipped, and having so much wealth and so many children. All of that was of no avail to them and could not protect them in the slightest from the punishment of Allah when the command of the Lord came. Nothing is impossible for Him when He wants it to happen in the heavens or on earth.'
(Verily, He is All-Knowing, All-Able.) means, He knows all that exists and is able to do all things.
(And if Allah were to punish men for that which they earned, He would not leave a moving creature on the surface of the earth;) meaning, if He were to punish them for all of their sins, He would destroy all the people of the earth and all that they own of livestock and crops. Sa`id bin Jubayr and As-Suddi commented on the Ayah:
(He would not leave a moving creature on the surface of the earth;) "This means, He would have stopped sending rain to them, and all the animals would have died as a result."
(but He gives them respite to an appointed term,) means, but He is delaying until the Day of Resurrection, when He will bring them to account and will reward or punish each one according to his deeds: He will reward those who obeyed Him and will punish those who disobeyed Him. He says:
(and when their term comes, then verily, Allah is Ever All-Seer of His servants.) This is the end of the Tafsir of Surah Fatir. All praise and gratitude is due to Allah.