ما تعبدون من دونه إﻻ أسماء سميتموها أنتم وآباوكم
"You do not worship besides Him but only names which you have named (forged) - you and your fathers -
Prophet Yusuf explained to them next that it is because of their ignorance that they worship false deities and give them names, for these names were forged and are being transferred from one generation to the next generation. They have no proof or authority that supports this practice, hence his statement to them,
ما أنزل الله بها من سلطان
for which Allah has sent down no authority,
or proof and evidence.
إن الحكم إﻻ لله أمر أﻻ تعبدوا إﻻ إياه
The command is for none but Allah. He has commanded that you worship none but Him;
He then affirmed that the judgement, decision, will and kingdom are all for Allah alone, and He has commanded all of His servants to worship none but Him.
He said,
ذلك الدين القيم
that is the straight religion,
`this, Tawhid of Allah and directing all acts of worship at Him alone in sincerity, that I am calling you to is the right, straight religion that Allah has ordained and for which He has revealed what He wills of proofs and evidences,'
ولكن أكثر الناس ﻻ يعلمون
but most men know not.
and this is why most of them are idolators,
وما أكثر الناس ولو حرصت بمومنين
And most of mankind will not believe even if you eagerly desire it. (12:103)