Allah said next,
(But (as for) their brothers they plunge them deeper) in reference to the devils' brothers among mankind. Allah said in another Ayah,
﴿إِنَّ الْمُبَذرِينَ كَانُواْ إِخْوَنَ الشَّيَـطِينِ﴾
(Verily, the spendthrifts are brothers of the Shayatin) ﴿17:27﴾ for they are followers of the Shayatin, who listen to them and obey their orders.
﴿يَمُدُّونَهُمْ فِى الْغَىِّ﴾
(They plunge them deeper into error) the devils help them commit sins, making this path easy and appealing to them
﴿ثُمَّ لاَ يُقْصِرُونَ﴾
(and they never stop short) for the devils never cease inciting mankind to commit errors. `Ali bin Abi Talhah reported that Ibn `Abbas commented on Allah's statement,
﴿وَإِخْوَنُهُمْ يَمُدُّونَهُمْ فِى الْغَىِّ ثُمَّ لاَ يُقْصِرُونَ ﴾
(But (as for) their brothers they plunge them deeper into error, and they never stop short.) "Neither mankind stop short of the evil that they are doing nor the devils stop short of luring them. '' Therefore,
(they never stop short) refers to the devils getting tired or stopping their whispering. Allah said in another Ayah,
﴿أَلَمْ تَرَ أَنَّآ أَرْسَلْنَا الشَّيَـطِينَ عَلَى الْكَـفِرِينَ تَؤُزُّهُمْ أَزّاً ﴾
(See you not that We have sent Shayatin against the disbelievers to push them to do evil) ﴿19:83﴾ persistently luring the disbelievers to commit evil, according to Ibn `Abbas and others.
﴿وَإِذَا لَمْ تَأْتِهِم بِـَايَةٍ قَالُواْ لَوْلاَ اجْتَبَيْتَهَا قُلْ إِنَّمَآ أَتَّبِعُ مَا يِوحَى إِلَىَّ مِن رَّبِّى هَـذَا بَصَآئِرُ مِن رَّبِّكُمْ وَهُدًى وَرَحْمَةً لِّقَوْمٍ يُؤْمِنُونَ ﴾
(203. And if you do not bring them a miracle, they say: "Why have you not brought it'' Say: "I but follow what is revealed to me from my Lord. This (the Qur'an) is nothing but evidences from your Lord, and a guidance and a mercy for a people who believe.'')